A method for improving drastically both the selectivity and yield of
hydrogen peroxide in the direct oxidation of hydrogen to hydrogen
peroxide over a solid catalyst comprising palladium, which comprises:
i) depositing on the solid catalyst at least two halogen containing
compounds, one compound essentially comprising bromine and second
compound essentially comprising fluorine with the bromine to palladium
and fluorine to palladium atom ratios in the range from 0.02 to 20 and
from 0.01 to 50, respectively; ii) decomposing the halo compounds
deposited on the solid catalyst by calcination at a temperature above
200.degree. C. under inert, reducing or oxidizing gas atmosphere or under
vacuum; and iii) contacting the solid catalyst obtained from step (ii)
with a gas mixture consisting of hydrogen and oxygen or air or O.sub.2
enriched air in an aqueous reaction medium, comprising a mineral acid at
the following reaction conditions: concentration of mineral acid in the
reaction medium above 0.001 mol/dm.sup.3, concentration of the solid
catalyst in the reaction medium above 0.01 g/dm.sup.3, H.sub.2/O.sub.2
mole ratio in the gas mixture in the range from 0.01 to 10, flow rate of
the gas mixture in the range from 50 cm.sup.3/g catalyst/h to 50,000
cm.sup.3/g catalyst/h, gas pressure at least 0.9 atm, and temperature
below 100.degree. C. and contact period of the reaction medium at least
0.01 h, is disclosed.