Two series of composites, i.e., polyvinyl alcohol (PVA)/oxidized starch (OST)/exfoliated alpha-zirconium phosphate (POST-ZrPn) and PVA/starch (ST)/exfoliated cc-zirconium phosphate (PST-ZrPn), were fabricated using a casting and solvent evaporation method. The composites were characterized by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), tensile testing, and moisture uptake. Compared with PST-ZrPn, POST-ZrPn films with the same component ratio showed higher tensile strength (sigma(b)), lower elongation at break (epsilon(b)) and improved water resistance. Additionally, in the POST-ZrPn series, sigma(b) and epsilon(b) increased with an increase in alpha-zirconium phosphate (alpha-ZrP) loading; however, higher alpha-ZrP loads resulted in the aggregation of alpha-ZrP particles. Compared with POST-ZrP0, the values for sigma(b), sigma(b), and water resistance of POST-ZrP3, containing 1.5 wt % alpha-ZrP, were increased by 128.8%, 51.4%, and 30.2%, respectively. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 1089-1097, 2010