In this study, the inhibitive effect of synthesized 2-(3-pyridyl)-3,4-dihydro-4-quinazolinone (PDQ) as a new corrosion inhibitor for mild steel in 0.1 M hydrochloric acid media is investigated employing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. The results show PDQ reduces anodic dissolution, retards the hydrogen evolution reaction and its adsorption obeys the Langmuir's adsorption isotherm. By increase in temperature, corrosion current density increases, however, its increase is lower in the presence of PDQ. By increase in temperature from 25 degrees C to 45 degrees C the inhibition efficiency decreases from 93% to 83% in solution containing 200 ppm inhibitor. Thermodynamic adsorption parameters show that PDQ is absorbed by a spontaneous exothermic process and its adsorption mechanism is combination of physical and chemical style. (C) 2010 Elsevier B.V. All rights reserved.