Thiadiazole, as a corrosion inhibitor for mild steel in 1 M hydrochloric acid has been investigated using weight loss method and Scanning Electron Microscopy (SEM). The results showed that this inhibitor revealed a good corrosion inhibition at low and high concentrations. The optimum concentration of the investigated inhibitor showing the highest inhibition efficiency was also evaluated at four different temperatures in the range between 303 and 333 K. The inhibition efficiency was found to increase with increase in concentration of the inhibitors but decrease with rise in temperature. The adsorption the corrosion inhibitor on the mild steel surface in acidic media follows a Langmuir isotherm. Thiadiazole as corrosion inhibitor was prepared and it chemical structure was elucidate using Fourier transformer infra-red (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy.