A novel method of measuring heat of adsorption of gases on metal films is described. The method is based on use of a LiTaO3 pyroelectric crystal to monitor surface temperature changes of a film which are brought about by adsorption of gas from a pulsed molecular beam generated in a quasi-effusion source. Calibration of the calorimeter is performed by pulsed laser radiation. Advantages of this approach are briefly discussed and its potentialities outlined.