To intensify ethanol fermentation of lactose, a co-immobilized biocatalyzer was used. It consisted of yeast cells of Saccharomyces cerevisiae co-immobilized with beta-galactosidase preparation from A. oryzae. The experiment was focused on the improvement of biocatalyzer operational stability. An increase in the concentration of a carrier (2% calcium alginate) did not improve the effectiveness of binding beta-galactosidase. However, its initial cross-linking with glutaraldehyde and its co-immobilization with distillery industrial yeast produced a stable biocatalyzer able to ferment mash from permeate (12% lactose) with an average efficiency of 6.5% v/v of alcohol during 10 experimental series (30 days).