The paper presents the results obtained when using Mannich bases (and derivatives) as corrosion inhibitors in saline environment, for different types of steels, with various alloying elements. The Mannich basis (ketonic combinations with naphtenic and nitrogen containing rings) were synthesized as such (polar) and as chlorhydrates (ionic) and used in corrosion experiments, in concentrations varying from 0….1300 ppm. The corrosion experiments were performed by potentiodynamic polarization studies. Based on the polarization curves, the corrosion current density and rate were calculated. The inhibitor efficiency was evaluated and based on these values the protection mechanisms was discussed.