N,N′-Methylenediacrylamide has been evaluated as a corrosion inhibitor for mild steel electrodes in 0.5 M HCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy, and polarization resistance measurements. According to the experimental results, inhibition efficiency increased with increasing inhibitor concentration. Potentiodynamic measurements showed that the presence of inhibitor molecules decreases cathodic and anodic currents and shifts corrosion potential to a more positive potential region. Adsorption of the inhibitor molecules to the mild steel surface obeyed the Langmuir adsorption isotherm. Adsorption free energy was calculated from the adsorption isotherm as −26.8 kJ mol−1. The negative value of ΔGads showed that the adsorption process is spontaneous for the studied conditions. In addition, measurements were carried out at different solution temperatures to determine temperature dependence of the adsorption process. At all studied temperatures, the inhibitor molecule protected mild steel electrodes with the same effect. The effect of immersion time on corrosion of mild steel was also tested in this study.