Copper-doped quantum dots of ZnSe(S) synthesized via microwave-heating conditions were used as photocatalyst in the photo-degradation of methylene blue (MB), methyl violet (MV) and victoria blue (VB) under UV irradiation (302 nm) in aqueous phase and at pH 6.5. Quantum dots were characterized by High Resolution Transmission Electron Microscopy (HR-TEM), X-ray diffraction (XRD), UV-Vis, photoluminescence and Fourier transform infrared (FT-IR) spectroscopy. The degradation of MB, MV and VB were monitored using High Performance Liquid Chromatography (HPLC) at 660 nm, 590 nm and 610 nm, respectively. Degradations percentages of 46%, 88% and 90% of MB, MV and VB, respectively, were achieved in presence of 1000 mg/L of quantum dots and 6 hours of UV-irradiation. Cu-doped ZnSe(S) QDs evidenced a remarkable capability to degrade cationic organic dyes as single components and in mixtures.