The physical properties of poly(ethylene oxide) (PEO) composites containing natural iron oxides with different concentrations 2, 4, 6, 8, 10, 15, and 20% by weight were studied. Powder of iron oxides of 63-mu m particle size was casted with PEO polymer. Absorption UV spectra were collected in the wavelength range 300800 nm by using a spectrophotometer. The optical energy gap and energy tail widths of localized states of the prepared composites were determined from Urbach formula. The electrical properties were studied using AC impedance measurements performed at different temperatures and in frequency range 100 kHz to 1 MHz. Impedance, dielectric constant, dielectric loss, and AC-conductivity showed frequency and temperature dependence. The thermal conductivity of the composites was studied as a function of iron oxides concentration and in temperature range 2050 degrees C. It was found that the thermal conductivity of the composites increases with filler concentration and temperature. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012