To inhibit the corrosion of carbon steel in water and aqueous solutions various organic compounds including salicylic acid and its derivatives have been successfully used. However, their protective properties in solution in the presence of Cl-, SO42-, and NO3- ions are greatly reduced, since the latter have harmful effect on the protective film formed on the corroding surface in the presence of inhibitors. Additionally, known inhibitors are used in high concentrations along with other components, thus making them difficult to use. In this comunication we present a heteronuclear salicylate complex [FeSr2(SalH)2(Sal)2(NO3)(DМАА)4], where SalH-= C6H4OHCOO- (mono deprotonated), Sal2-=C6H4(O-)COO- (bi deprotonated), DMAA= dimethylacetamide (C4H9NO), at a concentration of 0.05-0.75 g/L, that was used as a corrosion inhibitor for closed steel pipe with the water supply. By means of various physical methods (gravimetric, electrochemical, X-ray, UV and IR spectral analysis) the mechanism of inhibition was discovered. It was shown the effect of time and concentration of complex on the interaction process of the inhibitor and its degradation products with the ionized iron and on the formation of protective coating layers on the deteriorated surface. It was found that even small concentrations of the substance reduce the corrosion rate more than 11 times, providing a degree of protection Z, equal to 91%. The advantage of the presented inhibitor is that it provides a uniform corrosion inhibition in time.