The corrosion inhibition behavior of praziquantel for mild steel in 1 M HCl was studied by theoretical and electrochemical measurements. Tafel polarization measurement indicates that the praziquantel inhibitor acts as a mixed type. The corrosion rate decreases with the increasing concentration of inhibitor in 1 M HCl. The effect of inhibition is attributed due to the adsorption of inhibitor molecule on it and obeys the Langmuir adsorption isotherm. Adsorption parameters reveal that the adsorption process is exothermic and spontaneous. The quantum chemical parameters support the result obtained by electrochemical techniques. The surface morphology as SEM images shows the formation of a passive layer over the metal surface is an indication of the reduction in the corrosion rate.