The inhibition efficiency of previously prepared compounds namely, phthalimide derivatives on the corrosion of C-steel in 1 M HCl solutions has been studied using weight loss and electrochemical polarization methods. The results showed that the inhibition efficiency of the investigated compounds was found to depend on the concentration and the nature of the inhibitor. The effect of temperature on the corrosion behavior of C-steel in 1 M HCl without and with the inhibitors was studied in the temperature range from 303 to 333K. The activation and thermodynamic parameters for dissolution Δ Ea*,ΔH * and ΔS * were calculated. The inhibitors were adsorbed on the C-steel surface according to Langmuir adsorption isotherm.