Absorption and desorption of H by NbMo alloys at high temperature

► The kinetics of H absorption by NbMo alloys at high temperature is a first order reaction. ► The activation energy of the process, of about 1 eV, increases with increasing Mo content. ► The rate limiting process below 1100 K is H permeation through an oxide film. ► Above 800 K, in the presence of H, higher valence oxides are reduced to lower valence ones. ► The thickness of the oxide film estimated from absorption data was of the order of 1 μm.