Oxidation of ethanol to acetaldehyde is of relevance to synthetic chemistry and development of sensors for detection of gas phase ethanol. It is demonstrated by gas phase analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) that a Pt/WO3 composite shows significant activity in oxidative dehydrogenation of ethanol to acetaldehyde at room temperature. DRIFTS also demonstrates consecutive surface chemistry occurs, yielding predominantly ethyl acetate. The oxidation state of the most active Pt particles is determined to be Pt0, rather than PtO, by studying variations in catalyst preparation methodology, and characterization of various samples by X-ray photoelectron spectroscopy. Illumination has very little effect on surface reactivity and selectivity, but promotes formation of gas phase acetaldehyde.