Inhibition effect of some fatty acid oxadiazoles on the corrosion of mild steel (MS) in aqueous solution containing 1 N HCl was investigated by weight loss, potentiodynamic polarization technique, electrochemical impedance spectroscopy and scanning electron microscopy. The adsorption of these compounds was found to obey Langmuir adsorption isotherm. Various thermodynamic parameters were calculated to investigate the mechanism of corrosion inhibition. The effect of inhibitor concentration, solution temperature, immersion time and acid concentration on the corrosion of mild steel has also been investigated by weight loss technique. Scanning electron microscopy (SEM) is used to examine the surface morphology of the mild steel samples both in absence and presence of inhibitor at optimum concentration. Potentiodynamic polarization data showed that the compounds studied are cathodic type inhibitors in the acid solution. Electrochemical impedance spectroscopy was also used to investigate the mechanism of the corrosion inhibition.