The H-2 + 1/2O(2) reversible arrow H2O reaction on platinum at 700 and 1300 K has been studied. A stagnation flow geometry was used with a gas mixture of H-2 and O-2 at pressures between 0.10 and 10 Torr. Comparing SHG results with simulations using different reaction parameters, it was concluded that E-H20(f) approximate to 0.7 eV, E-OH(f) approximate to 0.7 eV, and E-OH(d) approximate to 2.6 eV. LIF measurements showed an ambiguity in the choice of main water-producing channel. Both hydrogen addition with low sticking coefficients and hydroxyl disproportionation with high sticking coefficients are plausible.