The electrochemical behavior of nickel, Inconel600, Incoloy800 and 316 stainless steel in different concentrations of HNO3 solutions was investigated using the cyclic voltammetry technique. . All the curves in the anodic cyclic voltammetry are characterized by an anodic dissolution peak (A) followed by a passive region (B), before oxygen evolution. On the other hand incoloy800and 316 stainless steel show an additional dissolution peak (C) and trans passive region followed by oxygen evolution. In the cathodic branch of the CVS there is one cathodic peak in the case of Ni. Inconel600 and Incoloy800.On the other hand, there is an unexpected peak in case of 316 stainless steel.This peak appeared on the anodic branch.All the anodic and cathodic peaks are interpreted. The passivation of Ni was explained based on the formation of NiO. In the alloys the passive layer was mainly composed of Ni+2, Fe+3and Cr+3 in Inconel600, Incoloy800, and Mo+6 in case of 316 stainless steel. The role of Cr+3 and Mo+6ions in the reinforcement of the passive film is explained.