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The effect of addition of TiO2 and the influence of type of binder, surface roughness and micro/macro-structure on photoactivity have been evaluated on mortars with four types of cements and three roughness.The classification according to photocatalytic efficiency was the same for both NOx degradation and self-cleaning in function of mixes composition (Portland cemen≈calciurn aluminate cement>fly ash>slag mortars).These differences have been attributed to redox potential of the aqueous phase of pores network and the photoabsorption energies of cementitious matrix components.Concerning the roughness and structure, it was found that the available active surface is a necessary parameter for evaluating photocatalytic efficiency.Thus,during the process of fabrication photocatalytic mortars, the chemical composition of cementitious matrix, final texture and microstructure of the material must be carefully selected to accomplish the requirements of photocatalytic efficiency.