Photocatalytic processes over semiconductor surfaces have attracted significant attention in recent years as potentially efficient, environmentally friendly and low cost methods for water/air purification as well as for hydrogen production by splitting of water. The process involves the irradiation of a semiconductor material like titanium dioxide (TiO2) with light energy equal to or greater than its band gap energy (Ebg). This may cause a valence-band electron to be excited to the conduction band, causing charge separation. The photogenerated electrons and holes can then migrate to the surface and participate in subsequent dark, oxidation-reduction reactions with species adsorbed on the photocatalyst surface to yield final products. For a semiconductor photocatalyst to be efficient, the different interfacial electron processes involving e- and h+ must compete effectively with the major deactivation process involving electron-hole recombination, which may occur in the bulk or at the surface. This is of primary importance to allow the efficient utilization of the exciting photon energy. This presentation will begin by describing semiconductor photocatalyst nanostructuring strategies used to retard electron-hole recombination, focusing on the work carried out at Nottingham. It will then present the engineering fundamentals of photocatalytic reactor design, photon transport and reactor modeling with examples of applications to indoor air purification and water purification. The presentation will finish with an overview of the “Solar-Hydrogen” project sponsored by E.ON, which aims at producing “green” hydrogen on an environmentally-friendly and cost-effective basis. The new process, which combines solar driven cleavage of water and degradation of organic compounds, will be able to produce hydrogen fuel at ambient conditions with the use of three abundant and renewable sources: solar light, biomass and water. For more information about this seminar, please contact: Hugo Destaillats510-486-5897