EX-1

Exhibit 1

FORM 51-102F3

MATERIAL CHANGE REPORT

Item 1 – Name and Address of Company

Cameco Corporation (“Cameco”)

2121 – 11th Street West

Saskatoon, Saskatchewan S7M 1J3

Item 2 – Date of Material Change

July 29, 2020

Item 3 – News Release

The news release relating to the material change described in this report was issued by Cameco via Intrado GlobeNewswire on July 29, 2020. A copy of the news release has been filed on SEDAR and is available at www.sedar.com.

Item 4 – Summary of Material Change

On July 29, 2020 Cameco announced its plan to restart operations at the Cigar Lake uranium mine in northern Saskatchewan in September, subject to certain conditions.

Item 5 – Full Description of Material Change

On July 29, 2020 Cameco announced its plan to restart the Cigar Lake mine at the beginning of September (the “Cigar Lake Restart”), providing it is safe to do so. The Cigar Lake Restart will be subject to Cameco’s ability to establish safe and stable operating protocols among other factors, including availability of the necessary workforce and an assessment of how the COVID-19 pandemic is affecting northern Saskatchewan. With the uncertainty remaining about Cameco’s ability to restart and continue operating the Cigar Lake mine, the delays and deferrals of project work and therefore the resulting production rate in 2020 and 2021, Cameco believes the current plan represents an appropriate balance of the commercial considerations affecting its decision. Should the Cigar Lake Restart occur as planned and maintain continued operations, Cameco is targeting its share of 2020 production to be up to 5.3 million pounds in total, and will not be able to make up the lost production.

Item 6 – Reliance on subsection 7.1(2) of National Instrument 51-102

Not applicable.

Item 7 – Omitted Information

Not applicable.