In the present paper, different concentrations of chromium oxide (Cr2O3) nanoparticles were incorporated within PEO/CMC polymer blend to produce nanocomposite films using the casting method. The X-ray diffraction was performed on PEO/CMC-Cr2O3 nanocomposites. The main X-ray peaks of Cr2O3 were observed and defined as cubic structure and orthorhombic shape with an average particle size of the Cr2O3 ~ 50-80 nm. The decrease of some IR bands after the addition of Cr2O3 nanoparticles was found attributed to the interactions between PEO/CMC and Cr2O3. Effect of Cr2O3 nanoparticles on optical properties such as absorbance and optical energy gap (Eg) were characterized using UV-Vis spectroscopy. The Eg was reduced after the addition of Cr2O3 nanoparticles. The AC conductivity (sac), dielectric constant (ε′), dielectric loss (ε′′) and the dielectric modulus (M′ and M′′) were calculated at frequency range 0.1 Hz-7 GHz. The increases of direct conductivity (σdc) imply that the free charge density or of the charge mobility that results. The estimated values of both ε′ and ε′′ were decreased with increases of frequency. The addition of Cr2O3 nanoparticles causes the formation of a charge-transfer complex. The Cole-Cole plot between (M′ and M′′) shows a semi-circular shape confirm discuses according to a non‐Debye method.