<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>129 - Disclosure - INTEREST EXPENSE AND OTHER EXPENSE (INCOME), NET</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>P01_01_2013To06_30_2013</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001166708</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>us-gaap_InterestIncomeExpenseNetAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Interest Income (Expense), Net [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="P01_01_2013To06_30_2013" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>              &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif "&gt;  &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  23. &lt;u&gt;INTEREST EXPENSE AND OTHER EXPENSE (INCOME), NET&lt;/u&gt;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  For the three months ended June 30, 2013, non-related party  interest expense of $&lt;font style=" FONT-SIZE: 10pt"&gt;56,200&lt;/font&gt;  is comprised of $&lt;font style=" FONT-SIZE: 10pt"&gt;55,910&lt;/font&gt;  interest on convertible debentures, and $&lt;font style=" FONT-SIZE: 10pt"&gt;290&lt;/font&gt; interest on notes payable. For the  three months ended June 30, 2012, non-related party interest  expense of $&lt;font style=" FONT-SIZE: 10pt"&gt;68,754&lt;/font&gt; is  comprised of $&lt;font style=" FONT-SIZE: 10pt"&gt;47,538&lt;/font&gt; interest  on convertible debentures, and $&lt;font style=" FONT-SIZE: 10pt"&gt;21,216&lt;/font&gt; interest on notes payable.&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: left; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  For the three months ended June 30, 2013, $&lt;font style=" FONT-SIZE: 10pt"&gt;120,402&lt;/font&gt; other income, net is comprised  primarily of approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;50,000&lt;/font&gt; sales commission, $&lt;font style=" FONT-SIZE: 10pt"&gt;47,500&lt;/font&gt; return and retirement of year end  2012 stock bonuses granted to certain consultants, and  approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;22,000&lt;/font&gt; royalty  income on licensed patents. For the three months ended June 30,  2012, $&lt;font style=" FONT-SIZE: 10pt"&gt;3,830&lt;/font&gt; other income,  net is primarily comprised of approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;8,000&lt;/font&gt; loss on extinguishment of  convertible debentures offset by approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;12.000&lt;/font&gt; individually insignificant, net  other income transactions.&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  For the six months ended June 30, 2013, non-related party interest  expense of $&lt;font style=" FONT-SIZE: 10pt"&gt;125,050&lt;/font&gt; is  comprised of $&lt;font style=" FONT-SIZE: 10pt"&gt;123,620&lt;/font&gt;  interest on convertible debentures, $&lt;font style=" FONT-SIZE: 10pt"&gt;660&lt;/font&gt; interest on notes payable, and $&lt;font  style=" FONT-SIZE: 10pt"&gt;770&lt;/font&gt; other interest. For the six  months ended June 30, 2012, non-related party interest expense of  $&lt;font style=" FONT-SIZE: 10pt"&gt;185,529&lt;/font&gt; is comprised of  $&lt;font style=" FONT-SIZE: 10pt"&gt;144,719&lt;/font&gt; interest on  convertible debentures, and $&lt;font style=" FONT-SIZE: 10pt"&gt;40,810&lt;/font&gt; interest on notes payable.&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; MARGIN: 0pt 0px 0pt 0.25in; FONT: 10pt Times New Roman, Times, Serif"&gt;  For the six months ended June 30, 2013, $&lt;font style=" FONT-SIZE: 10pt"&gt;28,624&lt;/font&gt; other income, net is comprised  primarily of $&lt;font style=" FONT-SIZE: 10pt"&gt;93,826&lt;/font&gt; loss on  extinguishment of convertible debenture, and offset by  approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;72,000&lt;/font&gt; royalty  income on licensed patents, $47,500 return and retirement of year  end 2012 stock bonuses granted to certain consultants, and  approximately $&lt;font style=" FONT-SIZE: 10pt"&gt;3,000&lt;/font&gt; other  income, net of individually insignificant items. For the six months  ended June 30, 2012, $&lt;font style=" FONT-SIZE: 10pt"&gt;978&lt;/font&gt;  other expense, net is primarily comprised of approximately $&lt;font  style=" FONT-SIZE: 10pt"&gt;80,000&lt;/font&gt; loss on extinguishment of  convertible debentures, $&lt;font style=" FONT-SIZE: 10pt"&gt;34,730&lt;/font&gt; write-off as obsolete or down to  fair market value some of the merchandise acquired in asset  purchase discussed in Note 8. &lt;u&gt;ASSET PURCHASE&lt;/u&gt;, and almost  completely offset by $&lt;font style=" FONT-SIZE: 10pt"&gt;95,054&lt;/font&gt;  gain on forgiveness of legal accrual, and approximately $&lt;font  style=" FONT-SIZE: 10pt"&gt;19,000&lt;/font&gt; other income, net of  individually insignificant transactions.&lt;/div&gt;  &lt;/div&gt;        </NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for other income or other expense items (both operating and nonoperating). Sources of nonoperating income or nonoperating expense that may be disclosed, include amounts earned from dividends, interest on securities, profits (losses) on securities, net and miscellaneous other income or income deductions.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 225

 -SubTopic 10

 -Section S99

 -Paragraph 2

 -Subparagraph (SX 210.5-03.3,6,7,9)

 -URI http://asc.fasb.org/extlink&amp;oid=26872669&amp;loc=d3e20235-122688



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher SEC

 -Name Regulation S-X (SX)

 -Number 210

 -Section 03

 -Paragraph 3, 6, 7, 9

 -Article 5



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Other Income and Other Expense Disclosure [Text Block]</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>INTEREST EXPENSE AND OTHER EXPENSE (INCOME), NET</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.browniesmarinegroup.com/role/InterestExpenseAndOtherExpenseIncomeNet</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>2</NumberOfRows></InstanceReport>
