<?xml version="1.0" encoding="utf-8"?>
<InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.0.0.10</Version>
  <hasSegments>false</hasSegments>
  <ReportName>Accounting pronouncements</ReportName>
  <ReportLongName>0204 - Disclosure - Accounting pronouncements</ReportLongName>
  <DisplayLabelColumn>true</DisplayLabelColumn>
  <ShowElementNames>false</ShowElementNames>
  <RoundingOption />
  <HasEmbeddedReports>false</HasEmbeddedReports>
  <Columns>
    <Column>
      <LabelColumn>false</LabelColumn>
      <Id>1</Id>
      <Labels>
        <Label Id="1" Label="12 Months Ended" />
        <Label Id="2" Label="Dec. 31, 2009" />
      </Labels>
      <CurrencyCode>usd</CurrencyCode>
      <CurrencySymbol>$</CurrencySymbol>
      <FootnoteIndexer />
      <hasSegments>false</hasSegments>
      <hasScenarios>false</hasScenarios>
      <Segments />
      <Scenarios />
      <Units>
        <Unit>
          <UnitID>USD</UnitID>
          <UnitType>Standard</UnitType>
          <StandardMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </StandardMeasure>
          <Scale>0</Scale>
        </Unit>
        <Unit>
          <UnitID>USDEPS</UnitID>
          <UnitType>Divide</UnitType>
          <NumeratorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </NumeratorMeasure>
          <DenominatorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema>
            <MeasureValue>shares</MeasureValue>
            <MeasureNamespace>xbrli</MeasureNamespace>
          </DenominatorMeasure>
          <Scale>0</Scale>
        </Unit>
      </Units>
    </Column>
  </Columns>
  <Rows>
    <Row>
      <Id>2</Id>
      <Label>Accounting pronouncements [Abstract]</Label>
      <Level>0</Level>
      <ElementName>us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract</ElementName>
      <ElementPrefix>us-gaap</ElementPrefix>
      <IsBaseElement>true</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>true</IsAbstractGroupTitle>
      <IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow>
      <IsEquityAdjustmentRow>false</IsEquityAdjustmentRow>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsReverseSign>false</IsReverseSign>
      <PreferredLabelRole />
      <IsEPS>false</IsEPS>
      <FootnoteIndexer />
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <IsRatio>false</IsRatio>
          <DisplayZeroAsNone>false</DisplayZeroAsNone>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText />
          <NonNumericTextHeader />
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
          <DisplayDateInUSFormat>false</DisplayDateInUSFormat>
        </Cell>
      </Cells>
      <OriginalInstanceReportColumns />
      <ElementDefenition>No definition available.</ElementDefenition>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
    <Row>
      <Id>3</Id>
      <Label>Accounting pronouncements</Label>
      <Level>1</Level>
      <ElementName>us-gaap_ScheduleOfNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock</ElementName>
      <ElementPrefix>us-gaap</ElementPrefix>
      <IsBaseElement>true</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>false</IsAbstractGroupTitle>
      <IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow>
      <IsEquityAdjustmentRow>false</IsEquityAdjustmentRow>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsReverseSign>false</IsReverseSign>
      <PreferredLabelRole>verboselabel</PreferredLabelRole>
      <IsEPS>false</IsEPS>
      <FootnoteIndexer />
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <IsRatio>false</IsRatio>
          <DisplayZeroAsNone>false</DisplayZeroAsNone>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText>&lt;!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --&gt;
   &lt;!-- Begin Block Tagged Note 4 - us-gaap:ScheduleOfNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock--&gt;
   &lt;div style="margin-left: 0%"&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;table width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff; text-align: left"&gt;
   &lt;tr&gt;
       &lt;td width="3%"&gt;&lt;/td&gt;
       &lt;td width="97%"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="top"&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;4&amp;#160;&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;Accounting
       pronouncements&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
   &lt;/tr&gt;
   &lt;/table&gt;
   &lt;div style="margin-top: 6pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;table width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff; text-align: left"&gt;
   &lt;tr&gt;
       &lt;td width="3%"&gt;&lt;/td&gt;
       &lt;td width="97%"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="top"&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;a)&amp;#160;&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;Newly issued
       accounting pronouncements&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
   &lt;/tr&gt;
   &lt;/table&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       Accounting Standards Update (ASU) number
       &lt;font style="white-space: nowrap"&gt;2010-06&lt;/font&gt; Fair
       Value Measurements and Disclosures (Topic 820): Improving
       Disclosures about Fair Value Measurements. This update provides
       amendments to Subtopic
       &lt;font style="white-space: nowrap"&gt;820-10&lt;/font&gt; and
       are expected to provide more robust disclosures about
       (1)&amp;#160;the different classes of assets and liabilities
       measured at fair value, (2)&amp;#160;the valuation techniques and
       inputs used, (3)&amp;#160;the activity in Level&amp;#160;3 fair value
       measurements, and (4)&amp;#160;the transfers between Levels&amp;#160;1,
       2, and 3. The Company will adopt this update in 2010 and does
       not expect relevant impacts on fair value information currently
       disclosed.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In June 2009, the Financial Accounting Standards Board
       (&amp;#8220;FASB&amp;#8221;) issued an amendment to Interpretation
       No.&amp;#160;46(R) on the accounting and disclosure requirements for
       the consolidation of variable interest entities
       (&amp;#8220;VIEs&amp;#8221;). Subsequently, in December 2009, the
       Accounting Standards Update (ASU) number
       &lt;font style="white-space: nowrap"&gt;2009-17&lt;/font&gt;
       Amendments to FASB Interpretation No.&amp;#160;46(R) was issued. The
       amendments replace the quantitative-based risks and rewards
       calculation, for determining which reporting entity has a
       controlling financial interest in a VIE, with a qualitative
       analysis when determining whether or not it must consolidate a
       VIE. The newly required approach is focused on identifying which
       reporting entity has the power to direct the activities of a
       variable interest entity that most significantly impact the
       entity&amp;#8217;s economic performance and (1)&amp;#160;the obligation
       to absorb losses of the entity or (2)&amp;#160;the right to receive
       benefits from the entity. The amendments also require an
       enterprise to continuously reassess whether it must consolidate
       a VIE. Additionally, the amendments eliminated the scope
       exception on qualifying special-purpose entities
       (&amp;#8220;QSPE&amp;#8221;) and require enhanced disclosures about:
       involvement
   with VIEs, significant changes in risk exposures, impacts on the
       financial statements, and, significant judgments and assumptions
       used to determine whether or not to consolidate a VIE. The
       Company will adopt these amendments in 2010. We are currently
       assessing the potential impacts of this pronouncement and do not
       expect major changes to the reported financial information.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In June 2009, the &amp;#8220;FASB&amp;#8221; issued an amendment to the
       accounting and disclosure requirements for transfers of
       financial assets. Subsequently, in December 2009, the Accounting
       Standards Update (ASU) number
       &lt;font style="white-space: nowrap"&gt;2009-16&lt;/font&gt;
       Accounting for Transfers of Financial Assets&amp;#160;&amp;#8211; an
       amendment of FASB Statement No.&amp;#160;140 was issued. The
       amendments improve financial reporting requiring greater
       transparency and additional disclosures for transfers of
       financial assets and the entity&amp;#8217;s continuing involvement
       with them and also change the requirements for derecognizing
       financial assets. In addition, the amendments eliminate the
       exceptions for QSPE from the consolidation guidance and the
       exception that permitted sale accounting for certain mortgage
       securitizations when a transferor has not surrendered control
       over the transferred financial assets. The Company will adopt
       the amendments in 2010 and do not expect major effect to its
       financial statements.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       Accounting Standards Update (ASU) number
       &lt;font style="white-space: nowrap"&gt;2009-08&lt;/font&gt;
       Earning per share issued by the FASB provides additional
       guidance related to calculation of earnings per share. This
       guidance amends ASC 260.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       The Company understands that the other recently issued
       accounting pronouncements, that are not effective as of and for
       the year ended December&amp;#160;31, 2009, are not expected to be
       relevant for its consolidated financial statements.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;table width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff; text-align: left"&gt;
   &lt;tr&gt;
       &lt;td width="3%"&gt;&lt;/td&gt;
       &lt;td width="97%"&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="top"&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;b)&amp;#160;&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
       &lt;td&gt;
       &lt;b&gt;&lt;font style="font-family: Arial, Helvetica"&gt;Accounting
   standards adopted in 2009&lt;/font&gt;&lt;/b&gt;
   &lt;/td&gt;
   &lt;/tr&gt;
   &lt;/table&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       Accounting Standards Update (ASU) number
       &lt;font style="white-space: nowrap"&gt;2009-05&lt;/font&gt; Fair
       value measurements and disclosures issued by the FASB provides
       additional guidance related to address the lack of observable
       market information to measure the fair value of a liability.
       This guidance amends ASC 820. It is effective after the
       issuance. The Company already adopts these statements.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In June 2009, the FASB issued the FASB Accounting Standards
       Codification (Codification). The Codification became the single
       source for all authoritative GAAP recognized by the FASB to be
       applied for financial statements issued for periods ending after
       September&amp;#160;15, 2009. The Codification does not change GAAP
       and does not have an affect on our financial position, results
       of operations or liquidity.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In June 2009, we adopted a newly issued accounting standard for
       accounting and disclosures of events that occur after the
       balance sheet date but before financial statements are issued or
       are available to be issued. In particular, this statement sets
       forth (1)&amp;#160;the period after the balance sheet date during
       which management of a reporting entity should evaluate events or
       transactions that may occur for potential recognition or
       disclosure in the financial statements; (2)&amp;#160;the
       circumstances under which an entity should recognize events or
       transactions occurring after the balance sheet date in its
       financial statements; and (3)&amp;#160;the disclosures that an
       entity should make about events or transactions that occurred
       after the balance sheet date. The standard is effective for
       interim or annual periods ending after June&amp;#160;15, 2009. The
       Company already adopts this statement.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In June 2009, we adopted a newly issued accounting standard for
       fair value of financial instruments which requires disclosures
       about fair value of financial instruments for interim reporting
       periods of publicly traded companies as well as in annual
       financial statements. This standard also requires these
       disclosures in summarized financial information at interim
       reporting periods. This standard shall be effective for interim
       reporting periods ending after June&amp;#160;15, 2009, and we have
       not opted for early adoption of this standard for the
       three-month period ended March&amp;#160;31, 2009. The application of
       this standard will expand the Company&amp;#8217;s disclosures
       regarding the use of fair value in interim periods. The required
       information is disclosed in Note&amp;#160;22 (d).
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In January 2009, we adopted a newly issued accounting standard
       regarding disclosure of derivative instruments and hedging
       activities. As such, entities must now provide qualitative
       disclosure about objectives and strategies for using
       derivatives, quantitative disclosures about fair value amounts
       of and gain and losses on derivative instruments and disclosures
       about credit-risk related contingent features in derivative
       agreements on a quarterly basis regarding how and why the entity
       uses derivatives, how derivatives and related hedged items are
       accounted for under the new standard and how derivatives and
       related hedged items affect the entity&amp;#8217;s financial
       position,
   performance and cash flows. The required information is
       disclosed in Note&amp;#160;25. In addition, unrealized gains or
       losses on derivatives, previously reported net on balance sheet
       are presented gross as assets and liabilities. Comparative
       information for 2008 has been reclassified.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In January 2009, we adopted a newly issued accounting standard
       for noncontrolling interests. This new accounting standard
       clarifies that a noncontrolling interest in a subsidiary is an
       ownership interest in the consolidated entity that should be
       reported as equity in the consolidated financial statements and
       consolidated statements of changes in stockholders&amp;#8217; equity.
       Noncontrolling interests that could be redeemed upon the
       occurrence of certain events outside the Company&amp;#8217;s control
       have been classified as redeemable noncontrolling interest using
       the mezzanine presentation on the balance sheet between
       liabilities and stockholders&amp;#8217; equity, retroactive to all
       periods presented.
   &lt;/div&gt;
   &lt;div style="margin-top: 12pt; font-size: 1pt"&gt;&amp;#160;
   &lt;/div&gt;
   &lt;div align="left" style="margin-left: 3%; margin-right: 0%; text-indent: 0%; font-size: 10pt; font-family: Arial, Helvetica; color: #000000; background: #ffffff"&gt;
       In January 2009, we adopted a newly issued accounting standard
       that applies prospectively to business combinations for which
       the acquisition date is on or after the beginning of the first
       annual reporting period beginning on or after December&amp;#160;15,
       2008.
   &lt;/div&gt;
   &lt;/div&gt;
</NonNumbericText>
          <NonNumericTextHeader>&lt;!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --&gt;
   &lt;!-- Begin Block Tagged Note</NonNumericTextHeader>
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
          <DisplayDateInUSFormat>false</DisplayDateInUSFormat>
        </Cell>
      </Cells>
      <OriginalInstanceReportColumns />
      <ElementDefenition>Represents disclosure of any changes in an accounting principle, including a change from one generally accepted accounting principle to another generally accepted accounting principle when there are two or more generally accepted accounting principles that apply or when the accounting principle formerly used is no longer generally accepted. Also disclose any change in the method of applying an accounting principle, or any change in an accounting principle required by a new pronouncement in the unusual instance that a new pronouncement does not include specific transition provisions.</ElementDefenition>
      <ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 154
 -Paragraph 2, 17, 18

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Principles Board Opinion (APB)
 -Number 28
 -Paragraph 23, 24

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 01
 -Paragraph b
 -Subparagraph 6
 -Article 10

</ElementReferences>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
  </Rows>
  <Footnotes />
  <ComparabilityReport>false</ComparabilityReport>
  <NumberOfCols>1</NumberOfCols>
  <NumberOfRows>2</NumberOfRows>
  <HasScenarios>false</HasScenarios>
  <MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel>
  <SharesRoundingLevel>UnKnown</SharesRoundingLevel>
  <PerShareRoundingLevel>UnKnown</PerShareRoundingLevel>
  <HasPureData>false</HasPureData>
  <SharesShouldBeRounded>true</SharesShouldBeRounded>
</InstanceReport>
