This work is to study the inhibitory power of compound ferrocene (ferrocénylméthyl N-(o-cyano) aniline) (fc22), visà- vis the corrosion of steel XC70 PSL2 in an environment of aqueous sulfuric acid. The inhibitory power fc22 is evaluated by the electrochemical method, based on achieving equilibrium potential of steel in the corrosive medium followed by tracing the polarization curves that provides access to the parameters of corrosion (Bc, Ba, icorr, Vcorr, Ecorr…..) using Tafel curve. The results obtained shows that the compound has the largest fc22 inhibitory power when the concentration 20 ppm.