The influence of oil of citrus leaves (OCL) concentration and the effect of medium temperature on the carbon steel corrosion in aqueous 1.0 M hydrochloric acid was realized experimentally using electrochemical impedance spectroscopy, potentiodynamic polarization curves and gravimetric technique. Results showed that the OCL is the excellent inhibitor for steel corrosion and the polarization curves data revealed that the tested compound acts as a mixed type inhibitor with predominant anodic. The study of temperature effect was investigated and leads to the determination of thermodynamic activation parameters. Electrochemical impedance spectroscopy result exhibit one capacitive loop indicating that, the corrosion reaction is controlled by charge transfer process and the presence of this compound decreases the double layer capacitance and increases the charge transfer resistance. The oil of citrus leaves act by adsorption on the carbon steel surface according to a Langmuir isotherm adsorption model.