An unusual observation of rate retarding influence of Cu2+ On the TiO2-mediated photooxidation of uracil, thymine and 6-methyluracil has been made. This is explained on the basis of a short-circuiting redox role of Cu2+ in the photoprocess. Increase of calcination temperature of the TiO2 sample resulted in a decrease of its photocatalytic activity and also the extent of its UV absorption. The former effect is attributed to a decreased extent of TiO2 surface bound peroxo species while the latter is attributed to a decrease in the surface area of TiO2.