The invention relates to processes for coating metal surfaces and to corrosion resistant coating compositions for use in the processes. The compositions of the invention are solutions of a chromic acid salt of one or more organic bases having at least one straight or branched chain containing at least six carbon atoms in an organic solvent having a boiling point not greater than 250* C. at atmospheric pressure. The salts used are restricted to those which are sufficiently soluble in the solvent at 20* C. to provide a solution containing at least 0.2% CrO3 w/v in the solution. Preferred bases are primary, secondary or tertiary amines and quaternary ammonium bases. In a preferred embodiment the composition also contains a material capable of effecting reduction of at least a part of the hexavalent chromium in the composition. For particular applications in which the composition is applied to metals which have been pretreated, washed and not dried the composition also contains a surfactant and, if necessary, a solubilizing agent for the surfactant.