Response surface methodology (RSM) was used to analyze the effect of different additives glycerol level (X1) and plasticizer level (X2) on the objective (water solubility index, water absorption index, and Max. loading) attributes of a cornstarch/PHBV blended composite. A rotatable central-composite design (CCD) was used to develop models for the objective responses. The experiments were run at barrels temperatures 160, 160, 165, and 165 degrees C, respectively, with screw speed 40 rpm and complete feeding (filling ratio - 1). Responses were most affected by changes in plasticizer level (X2) and to a lesser extent by glycerol level (X1). Individual contour plots of the different responses were overlaid, and regions meeting the predicted optimum water solubility index of 4.34%, water absorption index of 4.55 g gel/g dry wt, and Max. loading of 370.06 N were identified at the plasticizer level of 21.06 g, and the glycerol level of 96.11 mL, respectively. These predicted values for optimum process conditions were in good agreement with experimental data. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1797-1804, 2011