The influence of different concentrations of tolytriazole in the presence of 0.1 M sulphuric acid on electrochemical and corrosion behaviour of steel both with and without different concentrations of copper cation was studied potentiokinetically. It was found that tolytriazole reduces the corrosion current, corrosion rate and increases the polarization resistance. The protective cation was incorporated into the protective layer formed on the electrode surface exposed to tested solution. It was found that at a concentration of 10(-1) M, Cut(++) cation strongly inhibited the corrosion rate rather than at lower cation concentration. The corrosion of the steel in 0.1 M H2SO4 is appreciably reduced by tolytriazole in combination with metallic copper cation, as a result of coadsorption. The corrosion potential, corrosion current, corrosion rate, polarization resistance, as well as activation energy and thermodynamic parameters were calculated at different temperatures.