In a process for oxidizing a hydrocarbon to the corresponding hydroperoxide, alcohol, ketone, carboxylic acid or dicarboxylic acid, a reaction medium comprising a hydrocarbon is contacted with an oxygen-containing gas in a reaction zone and in the presence of a catalyst comprising a cyclic imide. During the oxidation process, a portion of the reaction medium is continuously or intermittently removed from the reaction zone, is stripped of water and organic acid impurities and then returned to the reaction zone.