The inhibitory properties of benzotriazole (BTAH) and its hydroxy derivative, 1-hydroxy-benzotriazole (BTAOH) on copper corrosion, were compared in 3% NaCl solution using cyclic voltammetry (CV), immersion tests, profilometry and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDX). CV experiments showed rapid interaction of both inhibitors with a Cu surface, but only at high concentrations. Immersion tests under stationary conditions showed that BTAOH offered corrosion protection only at concentration of 10 mM. Moreover, it was not effective under stirring conditions at any of the concentrations investigated. In contrast, BTAH exhibited good corrosion inhibition ability in all immersion tests. BTAOH, at up to 1 mM, increased the surface roughness of Cu more than 3% NaCl solution alone, but a significant reduction of surface roughening was observed when BTAH was present. Porous cross-linked acicular structures and star-like structures were observed using SEM/EDX in the case of BTAOH treatment. When Cu was treated with BTAH, roundish surface structures composed of bent plates with toothed-like edges, acicular structures and non-porous few hundred nm thick plates were observed.