Photocatalytic processes taking place on TiO2 have been widely employed and investigated. However, nitrogen-containing substances have not received the same attention as other substrates. Mineralization of such compounds is expected to lead to the formation of N-2 gas, ammonium and/or nitrate ions through photooxidative and/or photoreductive pathways. Herein, we will focus the attention on how the chemical structure may influence both the ratio and the extent of formation of the inorganic nitrogen. This review will consider heteroaromatic compounds, containing two or three-nitrogen in the ring, and small molecules, that could be formed as intermediate during the degradation of more complex substrates (i.e. pesticides), such as amino-alcohols, and molecules containing amide groups and nitriles. The fate final of the nitrogen in all these structures has been rationalized on the basis of the nature of N-N and C-N bonds in which the organic nitrogen is involved.