A simple and modified chemical precipitation method is used for synthesis of different PEG assisted cadmium oxide nanoparticles. The prepared products were characterized by X-ray diffraction, Fourier transform infrared, ultraviolet, scanning electron microscopy and energy dispersive X-ray analysis. The XRD patterns revealed the cubic phases and calculated particle sizes are 36.42, 34.27, 33.54 and 35.21 nm for pure CdO with 2, 4 and 6 % PEG nanoparticles respectively, From these results, it can be observed that the average crystalline size decreases with increasing PEG concentration. The functional groups and band area of the product were established by FT-IR spectroscopy. The band gap energy of CdO nanoparticles increased from 2.54 to 2.94 eV by increasing PEG concentration .The surface morphology and element composition have been confirmed form SEM with EDX analysis. In addition, the photocatalytic performance of PEG assisted CdO nanoparticles with methylene blue indicated that the CdO can be utilized a good photocatalyst for degradation of methylene blue.