The heat capacity contribution due to the absorbed hydrogen atoms in palladium hydride at a composition of nearlv Pd2H was measured in a newly constructed adiabatic calorimeter over small temperature intervals from 16 to 340 K. Á residual entropy of 0.59±0.18 eu has been calculated from experimental data to exist at 0 K. It is concluded that Pd2H does not approach a completely ordered state at low temperatures and so is not a true compound. The shape of the heat capacity curve indicates the probability of covalently bound hydrogen at low temperatures with a dissociation process oc-curring as the temperature is varied. More evidence for this model isto begiven in the succeeding paper.