The objective of this proposal is to spectroscopically identify the nature of surface species formed during the addition of tert butyl hydroperoxide onto the surface of the Au-Pd/TiO2. It is expected that the decomposition of tert butyl hydroperoxide can produce reactive oxygen species (ROS) or radicals, such as ¿OH and tBuO¿, ¿OOH and tBuOO¿, tBu¿, in addition to decomposition products such as H2O, O2 and t-butyl alcohol. However, it has not previously been considered in any detail if the peroxide species formed can be adsorbed on the catalyst surface. Only recently we have shown that there is possibility of surface stabilised reactive oxygen species (ROS) with radical character produced by TBHP using indirect catalytic data and EPR spectroscopy. Investigation of the TBHP interaction with Au-Pd supported nanoparticles will allow us to determine which species are attached to the metal.