A new technique for measuring simultaneously adsorption rate and temperature variation in zeolites has been developed. The transient temperature process during the adsorption of a gas on zeolite was analyzed by means of a simple model. It was found that the diffusion of gases in zeolite crystals could be made almost isothermal if the experimental conditions were appro-priately designed. Thus the thermal effect on the determination of diffusion coefficient of gases in zeolite could be neglected.