Enzymatic esterification of glycerol and palmitic acid was performed in acetone expanded by CO2 at 40-60 degrees C and 65-85 bar. Novozyme 435, Lipozyme RM IM, Lipozyme TL IM and Lipomod 34P were screened to select a suitable enzyme for the study. The effects of additional water and molar ratio of glycerol to palmitic acid on the selectivity to mono- and di-acylglycerol were investigated. Response surface method was used to describe the dependency of pressure, temperature, and enzyme concentration on the conversion of palmitic acid. Optimum condition was finally selected at 85 bar, 50 degrees C and 25% of Novozyme 435 related to the amount of dissolved fatty acid. (C) 2011 Elsevier B.V. All rights reserved.