Chemical and physical treatment of olive oil mill effluent (OOME) was performed using iron and lime as complexing agents, Duolite XAD 761 resin as phenolic adsorbent and hydrogen peroxide as oxidant. We have shown that 10 g dm(-3) of ammonium iron(III) sulphate . 12H(2)O, or calcium dihydroxide were sufficient to precipitate more than 50% of the initial COD and remove 50% of the initial colour within a short contacting time. The aromatic adsorbent resin retained more than 50% of the colouring compounds (chromophores) corresponding to removal of more than 60% of the initial COD after treating three bed volumes of crude OOME. The efficiency depended on the volume treated. Hydrogen peroxide removed the substituents of the aromatic rings which resulted in a decrease in length of the colouring compounds in OOME. However, they were not completely degraded, leading to shorter wavelength absorption. This chemical treatment was efficient in colour removal but only 19% COD removal was possible. In all cases, simple aromatics were reduced, as determined by GPC analysis. The chemical and physical decolorization of OOME was efficient in reducing the toxic effect of recalcitrant compounds. The resultant OOME by each of these alternative treatments was readily degradable through anaerobic digestion.