An innovative experimental method to investigate the thermal decomposition of metal hydrides is presented. The method is based on an experimental setup composed of a differential scanning calorimeter connected through a capillary tube to a mass spectrometer. The experimental system allows the simultaneous determination of the heat absorbed and the hydrogen evolved from a metal hydride during thermal decomposition. This arrangement constitutes a coupled differential scanning calorimetry (DSC) and thermal desorption spectroscopy (TDS) technique. It has been applied to metal hydride materials to demonstrate the capability of the experimental system. A method to obtain the heat of decomposition of metal hydrides is described. It involves the measurement of an apparent decomposition heat as a function of the carrier gas flow.