A hydrophobic composite Pd-membrane catalyst, useful for the non-hazardous
direct oxidation of hydrogen by oxygen to hydrogen peroxide, without a gas
phase mixing of hydrogen and oxygen or air, having the general formula:
HPM (c)/SOMF (b)/M.sub.x Pd.sub.1-x (a)/IPM wherein, IPM is an inorganic
porous membrane, M.sub.x Pd.sub.1-x is a metal alloy, permeable only to
hydrogen gas, Pd is a palladium metal; M is a metal other than palladium,
or a mixture of two or more thereof; x is a mole fraction of the metal M
in the metal alloy (M.sub.x Pd.sub.1-x), a, in the round bracket, is a
weight of the metal alloy per unit area of IPM; SOMF is a surface oxidized
thin metal film comprising palladium b, in the round bracket, is a
thickness of SOMF; HPM is a hydrophobic polymer membrane and c, in the
round bracket , is a weight of the HPM per unit area of SOMF and a process
for producing the said catalyst.