The reducibility of different catalysts based on Ni (bulk and supported) used to obtain syngas is studied in. this work. Taking as test reaction the steam reforming of methane, it was possible to prove that the stability of catalytic systems is closely related with the reduction temperature determined by TGA-DTG. Higher difficulty in reduction of metallic phase implies higher interaction between Ni and Al oxides; this leads to higher stability of catalytic system exposed to severe thermal treatments.