The effect of benzotriazole (BTAH) on the anodic dissolution of copper in 1 M HCl solution was investigated by using a rotating disc electrode (RDE) and a rotating hemispherical electrode (RHSE). It was shown that the presence of Cu(I) (CuCl or CuCl2) on the copper surface is necessary to have the inhibitive effect of BTAH. Just below the current plateau, the effect of BTAH depends on the electrode geometry: for the RDE, the electrode surface remained partially active, the protection by BTAH occurred only on a ring at the edge of the electrode, whereas for the RHSE the surface is uniformly covered by a protective BTAH complex. For both electrodes without the presence of BTAH, a surface roughness develops during the copper electrodissolution that can be kinetically interpreted as a porous-like electrode with pores of finite size. In the presence of BTAH and for the RSHE, the size of the pores becomes semi-infinite. (C) 2001 Elsevier Science Ltd. All rights reserved.