Ru, Pt and Ph catalysts supported on titania, ceria or active carbon and a Mn/Ce composite oxide catalysts were prepared and their catalytic behavior in Wet Air Oxidation (20 bar O-2) of phenol and acetic acid were investigated. Phenol was found to be an easily oxidizable compound as 170 degrees C, while acetic acid was a very refractory molecule, even at 200 degrees C. Ru(5 wt.-%)/C is a very efficient catalyst for the WAO of acetic acid without any leaching of noble metal.