Treatability of RR-120 aqueous dye solutions using O-3 and O-3/UV was studied in a bench scale set-up. Reduction in colour and chemical oxygen demand (COD) under various PH and initial dye concentrations were investigated. Pseudo first order reaction rate was satisfactorily used for kinetic interpretations in destruction of the dye. The results showed that decolorization with O-3 was faster at neutral PH values. While use of UV had a small effect on ozonation at low pH values, UV radiation had a considerable effect at pH values of 7 and above. It was found that ozone utilization efficiency of higher than 95% could be attained in the experimental set up.