The response surface method was employed to study the effect of pH, sodium chloride concentrations and temperature on the solubility of pumpkin seed globulins (cucurbitin). The most significant variable was linear sodium chloride concentration, followed by the quadratic sodium chloride concentration. The coefficient of determination (R-2) was high for the chosen second-order polynomial model. Optimal conditions of solubility of protein isolate from pumpkin seeds were: pH of 7.69, sodium chloride concentration of 3.99% and temperature of 54 degrees C. By means of additional experiments, the adequacy of the suggested model was confirmed. (c) 2007 Elsevier Ltd. All rights reserved.