`Methanol, ethanol, propanol, butanol (and their mixtures), glucose, saccharose, starch (and their mixtures), phenol and formaldehyde were oxidized with air oxygen and/or hydrogen peroxide in aqueous solutions under UV irradiation and in presence of 10 alumina-supported cobalt-titanium and molybdenum-titanium catalysts to study the reduction of chemical oxygen demand of the media. The catalysts were prepared by impregnation of gamma-alumina granules with titanium tetrachloride, drying, calcination at 600 degrees C for 3 h, impregnation with cobalt nitrate or ammonium molybdate and final calcination at 600 degrees C for 6 h. The catalysts used showed high catalytic activity. The cobalt catalyst was more suitable for oxidation of carbohydrates; while the molybdenum one for oxidation of alcohols. Both types of catalysts were efficient in oxidation of phenol and formaldehyde.