Process for the oxidation of a hydrocarbon comprising partially oxidizing in a reaction zone, a mixture comprising a hydrocarbon and an oxygen-containing gas in the presence of a catalyst which is capable of supporting oxidation of the hydrocarbon. Prior to the partial oxidation, the mixture comprising the hydrocarbon and the oxygen-containing gas is passed through a heat exchanger which provides a pressure drop which acts to even the velocity profile and ensure that the reactants flow uniformly over the catalyst.