This study reports the first time that cheese whey wastewater has been treated by the hydrogen peroxide oxidation alone (uncatalytic reaction). This oxidation type was capable of eliminating the total phosphorus content in about 46–53%, regardless of the dose applied (1–7 g L⁻¹). For total phenols contents, the oxidation system was capable of reducing around 40% under the lowest concentration investigated (1 g L⁻¹). Similar results were obtained for calcium content with a reduction of 55%. Turbidity was reduced in about 90% when hydrogen peroxide was applied with concentrations of 2, 3 and 7 g L⁻¹. Characteristic absorbances were reduced in the range of 12–83% depending on the operating conditions. Chemical oxygen demand (COD) was recalcitrant to hydrogen peroxide oxidation alone (uncatalytic reaction), needing a post-treatment.