In recent years, the development of ecofriendly biodegradable packaging materials from natural polymers particularly agricultural products has received increasing attention in an attempt to substitute the existing nonbiodegradable petro-based polymers. The need for new polymeric materials with tailored properties has driven the interest of industry and academia toward polymer blends. Vegetable oils are known to possess varying amounts of triglycerides having different unsaturation in their chains. Blending of commercial polymers with vegetable oil derived polymers is, therefore, expected to show synergetic behavior in terms of compatibility, physical, and mechanical characteristics with the latter. In an attempt to develop a biodegradable packaging material, blends of poly(vinyl alcohol) (PVA) and castor oil epoxy (COE) were synthesized in the weight ratios of 70/30, 60/40, 50/50, 40/60, and 30/70 by a microwave method. The effect of COE component as well as microwave irradiation on the compatibility and microstructural properties of the blends was investigated using spectral, viscometric, thermal, and morphological techniques. We observed tremendous improvement in mechanical properties after microwave irradiation for 120 s in COE/PVA 70/30 blend due to optimum cross-linking through hydrogen bond formation among the blend components. These results were supported by the SEM as well the TEM data. (C) 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 96-109, 2011; View this article online at wileyonlinelibrary. com. DOI 10.1002/adv.20207