The invention relates to hydrogen peroxide manufacture, and catalyst therefor, by direct oxidation of hydrogen with oxygen in an acidic aqueous medium. The catalyst includes a Group VIII metal on a partially hydrophobic, partially hydrophilic support, such as Pd on fluorinated carbon. Improvements in H.sub.2 O.sub.2 selectivity and catalyst stability are achieved by adding a source of sodium and chloride ions to the reaction medium and, in the case of a fluorinated carbon support, adding a source of fluoride ions.