The effect of temperature on mechanical behaviors was observed in a Korean domestic Ca-bentonite which has been considered as a potential buffer material in the engineering barrier of a high level radioactive waste(HLW) disposal system. Laboratory tests have been conducted on Korean Kyeongju bentonite blocks that were compacted in different dry densities. Swelling pressure tests at various temperatures between 30 and 90 were carried out by supplying de-ionized water. The study revealed that with increases in temperature the bentonite swells faster, but its absolute value of swelling pressure decreases.