Mixed matrix membranes of poly(vinyl alcohol) and poly(vinyl pyrrilidone) blends were prepared by loading with phosphomolybdic acid (PMA) and their pervaporation (PV) properties were investigated for the PV separation of isopropanol. Membrane performance shown a dependence on the extent of PMA loading. The 4 wt % PMA-loaded blend membrane had the highest separation factor of 29991, which declined considerably at higher loading. The flux of 4 wt % PMA-loaded membrane was lower than that of nascent blend membrane. Feed water composition and temperature influenced the PV performance. Solubility selectivity was higher than diffusion selectivity. Degree of swelling was smaller after PMA loading exhibiting better separation ability. The PV results were analyzed using the Flory-Huggins theory and sorption was dominated by Langmuir's mode. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 711-719, 2011