We have recently demonstrated that it is possible to obtain structural information about adsorbed hydrogenous species from a variety of metal catalysts. We emphasise that this is unique capability, for the first time it is possible to gain structural information about adsorbed species on real catalysts. Using some test time we are able to determine a Pt-H distance of 1.88 A, in excellent agreement with single crystal measurements and ab initio results. However, the cell developed a leak during the latter part of the measurements which resulted in the formation of O-D as well as Pt-D. The aim of this proposal is determine the Pt-H distance for both the on-top and high coordination sites using both hydrogen and deuterium to unabiguously define these distances for the first time on a real supported metal catalyst.