The inhibition effect of triazolyl blue tetrazolium bromide (TBTB) on the corrosion of cold rolled steel (CRS) in 1.0M HCl and 0.5M H 2 SO 4 solution was investigated for the first time by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results show that TBTB is a very good inhibitor, and is more efficiency in 1.0M HCl than 0.5M H 2 SO 4 . The adsorption of TBTB on CRS surface obeys Langmuir adsorption isotherm. Polarization curves reveal that TBTB acts as a mixed-type inhibitor in both acids.