Experimental investigation shows that UV/hydrogen peroxide (H2O2) oxidation of a more concentrated phenolic wastewater can lead to economical savings. The savings can be achieved by the lower amount of H2O2 required and time needed to treat the wastewater. Phenolic wastewater can be concentrated by treating the bulk wastewater with activated carbon. The concentrated wastewater that is generated from activated carbon regeneration (assumed to be fully regenerated by steam) can then be treated with UV/H2O2. Experimental results show that H2O2 concentration goes through an optimum value where adding any more H2O2 will result in less effective removal of contaminants. Conductivity of treated wastewater increases sharply then drops down. This could be attributed to the presence of high molecular compounds, inorganic acids, and OH radicals.