Electrochemical and impedance experiments were carr ied out to evaluate the corrosion behavior of carbo n steel in aerated 1.0 M HCl solutions in the presence of 3,7- dimethylquinoxalin-2-(1H)-one (DQO) at 308K. The co rrosion rate of carbon steel was found to increase in the p resence this compound. The adsorption and inhibitor y effect of DQO on carbon steel surface in aerated 1.0 M HCl so lutions were then investigated in detail by potenti odynamic polarization and electrochemical impedance spectros copy (EIS). The data obtained indicate that quinoxa line behaves as a mixed-type inhibitor adsorbing onto th e carbon steel surface according to the Langmuir is otherm, with the negative ads G ° ∆ value of -47.47 kJ mol -1 signifying a spontaneous adsorption process. The c orrosion inhibition efficiency increased with DQO concentration in the range of 10 -6 -10 -3 M