A heat exchanger for an air-conditioning circuit of a vehicle. The heat exchanger enables heat exchange between fluids and has a surface in contact with one of the fluids. The surface is formed from aluminum and/or from aluminum alloy. The surface is coated with an alumina layer and a reinforcing layer. The reinforcing layer includes an organic substance and a mineral substance. The organic substance includes at least one polymer and the mineral substance is capable of reacting with the aluminum in order to form an anticorrosion material.