Hydrogen peroxide was used as an oxidant to modify the cuprite surface and enhance its sulfidization. Surface-adsorption and infrared spectroscopy measurements indicated that the modification of the cuprite surface with hydrogen peroxide before sulfidization increased the adsorption capacity of xanthate. Zeta potential, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry results showed that the modification with hydrogen peroxide increased the contents of S^2- and S_n^2- species on the cuprite surface. Microflotation tests showed that the recovery of cuprite increased from 61.74% to 83.30% after the modification of the surface with hydrogen peroxide. These results confirm that the modification of the cuprite surface with hydrogen peroxide enhances the sulfidization of cuprite, which in turn improves its flotation.