Corrosion inhibition of benzotriazole (BTAH) for 70/30 brass in 0.1 M NaCl has been evaluated by means of electrochemical polarization and solution analysis. Electrochemical polarization curves obtained in two different benzotriazole containing 0.1 M NaCl solutions, such as 1.2 x 10(-4) and 2.7 x 10(-2) M, showed that corrosion of brass was hindered up to 0.0 V in the first solution and up to 0.4 V in the second one. For the first solution the anodic polarization curve displays two potential regions. In the first anodic region between -1.75 and 0.0 V (SCE), benzotriazole addition enhances ZnO film formation. Cu(I) BTA film is also formed by electron transfer in this region. In the second region between 0.0 and 1.0 V (SCE) copper oxidizes to Cu(I) oxides and Cu(II) hydroxide with the formation of CuCl film. Insoluble Cu(I) BTA film complex is also formed on these oxide/hydroxide films. Solution analysis after constant potential polarization showed that brass fairly corroded in 2.7 x 10(-2) M BTAH + 0.1 M NaCl solution although potentiodynamic polarization curves show passivity till 0.4 V (SCE). An explanatory mechanism is proposed. (c) 2005 Elsevier B.V. All rights reserved.