In the present investigation, we synthesized copper (I) oxide nanoparticles (NPs) by the coprecipitation method. The obtained materials were characterized by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDXA), field emission scanning electron microscopy (FESEM), Transmission Electron Microscopy (TEM), and the Brunauer-Emmett-Teller (BET)/Barrett-Joyner-Halenda (BJH) Method. Surface areas and the average particle size were evaluated to be around 4.20 ± 0.04 m2 g−1 and 28 nm, respectively. Then, Ag/Cu2O NPs were synthesized by the same process, examined by X-ray diffraction, and the average particle size obtained was around 118 nm. The photocatalytic degradation of [1,3-Amino phenyl [4-Sulphonic acid][2,6-Dis azo phenyl] 4,4′sulphato ethyl [6′sulpho] ester of Sulphonic acid] (COG-423) was investigated with Cu2O and TiO2 NPs, Cu2O Microparticles (Micro-Ps) and Ag/Cu2O NPs under UV-C irradiation in the presence of hydrogen peroxide as auxiliary oxidant with three parameters including dopant concentration, intensity, and time, as the obtained experimental results showed a good agreement with theoretical values and succeeded to calculate the optimal conditions. Degradation efficiency with Cu2O Micro/NPs under UV-C irradiation (32 W), for 30 min. were determined to be 20.0% and 91.4% respectively, while for the synthesized TiO2 and Ag/Cu2O, NPs were 99.9%. The photocatalytic activity order was of the following nature: Ag/Cu2O ∼ TiO2 NPs > Cu2O NPs > Cu2O Micro-Ps. [ABSTRACT FROM AUTHOR]