A semi-continuous process has been developed for the synthesis of TiO2 powders: a sol-gel reaction, using titanium isopropoxide as precursor and acetylacetone as chelating agent, followed by supercritical drying is performed. The obtained powders have been characterized by X-ray diffraction, SEM, TEM, BET method and OH surface groups measurements. The recovered solids are always crystallized in the anatase structure with particle size ranging from 8 to 13 nm. Surface at ea and OH surface groups density are around 100 m(2).g(-1) and 0.6 x 10(-3) mol .g(-1) respectively. The photocatalytic activity of the elaborated powders has been studied following the degradation of phenol and compared to that of two commercial powders (P25 Degussa and Acros).