The general objective of GEMMA Project is to qualify and codify the selected structural materials for the construction of Generation IV reactors, as envisaged within the European Sustainable Nuclear Industrial Initiative (ESNII). The structural materials, to be considered in the GEMMA project, are those selected by the designers of the ESNII systems for fuel cladding and, in some cases, for the main vessel and the internals. Their qualification means that their resistance to harsh exposure conditions of high temperature, highly corrosive environment and intense flux of fast neutrons, will be experimentally verified and/or numerically modelled. The applicability of materials to the reactors' construction implies also that relevant welded joints will be tested as well as corrosion protection treatments. Even the corrosion resistance of new Alumina Forming Alloy steels and surface treatments will be tested in representative conditions.