Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion inhibition of 1-acetylindoline-2,3-dione (Ind2) for carbon steel in hydrochloric acid. It is found that the inhibition efficiency of Ind2 increases with the increase of the concentration of Ind2. The results show that Ind2 possesses excellent inhibiting effect for the corrosion of carbon steel and the inhibitor acts as mixed-type inhibitor. The adsorption process is spontaneous and follows Langmuir adsorption isotherm model. The surface adsorption of the inhibitor molecules decreases the double-layer capacitance and increases the polarization resistance. The results obtained from the different techniques were in good agreement which prove the validity of these tools in the measurements of the tested inhibitor.