Saccharomyces cerevisiae was immobilized in polyacrylamide gel beads. The effect of each gel constituents on whole cell alcohol dehydrogenase activity of yeast were studied. Prior to entrapment the cells were permeabilized by cetyltrimethylammonium bromide (CTAB) where 27% increase in activity was obtained. The permeabilized entrapped cells were treated with different detergents. CTAB was found to increase the gel permeability. The optimum concentration of nicotinamide adenine dinucleotide (NAD) was determined to be 30 muM. The optima concentration of ethanol for permeabilized cells, permeabilized and entrapped yeast cells were 3 and 2 M, respectively. Entrapped yeast cells converted almost 32.4 and 45% ethanol and 2-butanol to their respective aldehydes. (C) 2003 Elsevier Science Inc. All rights reserved.