As geosynthetic clay liners (GCLs) are becoming integral components of modern municipal solid waste landfill lining systems, increased interest is directed at investigating their behaviour under different environmental stresses such temperature, chemical compatibility, etc. Such stress can be due to biological decomposition of organic matter within municipal solid waste involving exothermic reactions leading to heat generation and consequently, increased temperatures within the waste mass as well as at the landfill base. This paper presents the results of an experimental investigation on temperature effects on the volume change and hydraulic conductivity behaviour of GCL specimens. A Rowe cell modified to handle elevated temperatures up to 60oC was utilized. Series of thermal consolidation and hydraulic conductivity tests were conducted under saturated condition at different elevated temperatures, varying from 20oC to 60oC, and different stress levels.