A comparative study of the interfacial reactions between Pd anda‐Ge:H, deposited atTS=150 °C (low temperature, LT) and atTS=200, 300 °C (high temperature, HT), was carried out by x‐ray diffraction and Auger electron spectroscopy after sample annealing in the regime ofT=200–300 °C andt=1/4–4 h. It was found that the Pd/a‐Ge:H(LT) formed a much more stable Pd2Ge interfacial layer, compared to the Pd/a‐Ge:H(HT) system in which the Pd2Ge was transformed to PdGe. The main difference between the LT‐ and the HT‐a‐Ge:H films is probably the structure of the material. Whereas the HT films are compact, the LT‐a‐Ge films contain a network of voids which slow down the diffusion of Ge to the interface.