The corrosion inhibition of thiadiazole derivatives for brass in natural seawater has been evaluated by potentiodynamic polarisation and electrochemical impedance spectroscopic techniques. It was found that the inhibition efficiency of the thiadiazole derivatives, namely, 2-amino-5-ethyl-1,3,4- thiadiazole(AETD), 2-amino-5-ethylthio-1,3,4-thiadiazole(AETTD) and 2-amino-5-tert-butyl-1,3,4- thiadiazole (ATBTD) increases with increase in concentration. The adsorption of thiadiazole derivatives on brass surface exposed to inhibitor-containing solutions was confirmed using SEM/EDX spectra and FT-IR spectra. Adsorption of these inhibitors on brass surface followed Langmuir adsorption isotherm. ICP-AES analysis confirms that dezincification was minimized to a greater extent in the presence of these inhibitors.