Coal ash/polyethylene oxide (ash/PEO) composite films were prepared by the solution casting technique. Scanning electron microscopy (SEM) micrographs indicated that the ash particles were dispersed and embedded well within the polymer matrix. The size of the ash particles in the PEO matrix was less than 3 mu m. The polarized optical microscopic (POM) analyses revealed that the pure PEO, upon crystallization, showed distinct crystalline spherulites of a considerable size. The size of the spherulites was decreased by the incorporation of ash particles into the polymer matrix, which might be due to the nucleation role of ash in ash/PEO composite, and resulted in small-sized spherulites. The differential scanning calorimetry (DSC) thermograms showed that the melting temperature (T(m)) of pure PEO was about 66 degrees C, while the T(m) peak shifted to a slightly lower temperature when ash was incorporated in the polymer matrix. The mechanical properties of the ash/PEO composites were enhanced up to an optimum level (ash wt. %) as compared to pure PEO. The thermograms from the thermogravimetric analyzer (TGA) indicated that the thermal stability of the ash/PEO composite shifted to a higher temperature, about 30 degrees C higher than pure PEO.