The effect of calcination temperature on the activity and some properties of low temperature water gas shift reaction catalysts has been investigated. The activities of catalysts have been determined using a fixed bed catalytic reactor. The following results may be deduced from the present study. 1. The catalysts' total surface area decreased with increasing calcination temperature, presumably due to the partial sintering of the catalysts particles. 2. The presence of an amorphous CuO phase within the structure of some catalysts may be related to the desirable conditions prevailing during synthesis of the latter. 3. Observation of a similar trend between the increase in copper crystallite particle size and enhancement of catalyst activities with increasing calcination temperature demonstrates the important contribution made by the copper crystallite phase to the overall activities of water gas shift reaction catalysts.