Organic synthesis through semiconductor photocatalysis has become an important research area in photochemistry in the last two decades. Significant examples of organic transformations employed for synthetic purposes are oxidation and reduction reactions, isomerization reactions, C-H bond activations and C-C and C-N bond forming reactions. The photocatalytic oxidation of organic compounds have been studied largely because the most common metal oxides and metal chalcogenide semiconductors have valence band edges that lie positive of the oxidation potentials of most organic functional groups. In contrast, photocatalytic reductions are less frequently found, because the reducing power of a conduction band electron is significantly lower than the oxidizing power of a valence band hole and because most reducible substrates do not compete kinetically with oxygen in trapping photogenerated conduction band electrons. The most significant and studied photocatalytic reductions have been water photoreductive hydrogen production, carbon dioxide reduction in presence of water to obtain methane and oxygen and nitrogen reduction with water to obtain ammonia and oxygen. In the present work we report three study cases for benzaldehyde, nitrobenzene and chromates carrying out the photocatalytic reduction in the presence of pure and modified titanium dioxide.