The inhibitory effect of aqueous extract of leaves of Holoptelea Integrifolia (HI) plant on the corrosion of mild steel in 1N HCl was investigated by using traditional weight loss method and electrochemical method. Organic moieties present in the extract are found responsible for effective performance of the inhibitor which was well supported by FTIR studies. Potentiodynamic polarization curves revealed that the inhibitor act as a mixed type inhibitor and the inhibition efficiency of up to 98.45 % can be obtained. The SEM morphology of the adsorbed protective film on the mild steel surface has confirmed the high performance of inhibitive effect of the plant extract. Temperature studies revealed that the the inhibition efficiency decrease with increasing temperature which suggests that it follows physisorption mechanism. Surface coverage values were tested graphically for suitable adsorption.