The corrosion inhibitor (thiazole-5-carboxylic acid) was tested in this study using a weight loss technique and at temperatures range from 30 to 50 °C, and concentrations range from 100 to 400 ppm. Since the corrosion inhibitor contains atoms of oxygen, nitrogen, and sulfur, as well as thiazole that can be inhibit the corrosion process, the corrosion inhibitor's efficiency decreases as temperatures rise to 40 and 50°C, due to the formation of a layer of film on the metal's surface, and because the corrosion inhibitor contains atoms of oxygen, nitrogen, and sulfur, as well as thiazole that can be inhibit the corrosion process. The reaction's thermodynamic characteristics, such as activation energy, enthalpy, entropy, and free energy of adsorption, were determined and were satisfactory in the inhibitory processes.