there is provided a process of producing p - benzoquinone , wherein hydroquinone and hydrogen peroxide are reacted in water , an aqueous inorganic acid solution , an inert organic polar solvent or a mixture of water with an inert organic polar solvent in the presence of a catalyst selected from the group consisting of iodine , hydrogen iodide , and iodine compounds of metals . according to the process , p - benzoquinone can be obtained from hydroquinone with the yield and the quality of the p - benzoquinone being high without requiring any special facilities , equipments and operations .