The anodic oxidation of metallic gold in acetonitrile, which is normally inhibited by traces of water causing passivation, can be promoted by halide catalysis. The deblocking mechanism is based on displacement of water by concurrent adsorption of halide ions. Only small quantities of halide, enough to cover the anode surface with a monoionic layer, are required for the process. The catalytic effect increases in the order Cl- < Br- << I-. The effect can be used for the easy preparation of Au+ solutions.