In this study, blends of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) were prepared by solution casting method to develop membranes. The addition of carboxymethyl cellulose (CMC) led to the stabilization of PVA and PEO blend system. PVA/PEO/CMC membranes of three compositions 90/10/5, 90/10/10, and 90/10/20 were prepared and were characterized by X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (DSC), and attenuated total reflectance-Fourier transform infra-red. It was found that the addition of CMC to PVA/PEO blend leads to significant visible changes in the miscibility of these two components. Swelling of blend membranes increased with the increase in concentration of CMC. The thermal stability and mechanical strength of the blended samples increased with increasing CMC content when compared with pure PVA and PVA/PEO blends. XRD and DSC showed decrease in crystallinity with the increase in CMC content. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013