Hydrogen peroxide has been found to form as a byproduct during fuel cell operation, which is linked to the degradation of the ion exchange membrane resulting in a shorter lifetime of the fuel cell. Using O 1s X-ray photoelectron spectroscopy and X-ray absorption spectroscopy we investigated the molecular oxygen adsorption on hydrogenated Pt(111) and found that adsorbed hydrogen promotes the formation of a hydrogen peroxide-like intermediate. Polarization dependent X-ray absorption spectroscopy reveals that the O-O molecular axis is close to parallel and the OH group is perpendicular to the surface.