The photooxidation of acetaldehyde on TiO2-SiO2 has been studied using UV-Vis irradiation in the range of 2.1 to 5.0 eV. It has been found that a large fraction of acetaldehyde undergo aldol condensation during dark oxidation forming crotonaldehyde. However, in presence of light the formation of CO2 and other partially oxidized species have been observed. The infrared assignments of surface intermediates along with mass spectral studies used to explore the reaction mechanisms of the photochemical reaction. In addition, a comparative study of the photocatalytic reactions on different surfaces will also be discussed.