The corrosion and passivation of tin in sodium berate (Na2B4O7) solutions at pH=8.35 were studied by potentiodynamic and cyclic voltammetry techniques. The effect of the following factors on the anodic dissolution and passivation of tin metal are discussed : concentration of berate ion, pH, potential scan rate, successive cyclic voltammetry, switching potential and progressive additions of halide ions. The primary passivation is attained when the metal is covered with a film of Sn(OH)(2) and/or SnO. Permanent passivity occurs when Sn(OH)(4) and/or SnO2 forms a continuous layer on the electrode surface. The anodic dissolution reactions are controlled by diffusion. In all experiments, the aggressive action of the halides decreased in the order Cl- > Br-. SEM examination confirms the occurrence of pitting corrosion in presence of halide ions. The pitting potential (E(pit)) decreases with increasing halide concentration.