This article deals with inhibitory action of some one- and two displace derivatives of mercapto-acetic acid (ODDMAA and TDDMAA) previously examined in neutral and week acidic systems on the corrosion of steel CT-3 quality in the system HCl (0,1 N solution)-kerosene. It has been established that in this system both ODDMAA and TDDMAA have inhibitory properties. However, given identical concentrations TDDMAA has higher protective effect in comparison with ODDMAA. Formerly obtained regularities of dependence “inhibitor structure-protective effect” have been confirmed.