Expired nizatidine drug (END) was studied as inhibitor for a-brass in 1M HCl utilizing weight loss (WL), and electrochemical methods namely, AC impedance (EIS), Potentiodynamic polarization (PP), and electrochemical frequency modulation (EFM) tests. The protection efficiency (%IE) was improved with raising in the dose of the expired nizatidine and decreases with raising the temperature. The (%IE) reaching maximum value 95 % at higher dose of expired nizatidine drug at 25°C. PP data indicated that nizatidine drug behaves like a mixed kind drug. The protection of a-brass corrosion by nizatidine can fit to the adsorption ability of nizatidine drug molecules onto the reactive sites of the a-brass surface. The adsorption of the drug follows Langmuir adsorption isotherm. The surface morphology of a-brass was investigated. The results obtained from different methods are in excellent agreement.