The study of sorption reactions of metal hydrides is the subject of numerous researches in connection with the development of a safe technology for hydrogen storage, and MgH2, in particular, is one of the most promising materials. Several efforts have been already carried out in order to understand the kinetic mechanisms involved in the MgH2 decomposition which is at the basis of H2 release. However, the role of additives and induced structural defects on the sorption cycles is not clear yet. With the purpose of supporting the reaction analysis we have developed an experimental protocol for the metallographic examination at high spatial resolution of partially desorbed MgH2 powders. In particular, this procedure allows cross-sectional analysis of powders embedded into conductive matrix, while the observation method produces a different contrast among metallic Mg, MgH2 and additive particles made of heavier materials.