Production of the bioemulsifier, emulsan, by Acinetobacter calcoaceticus RAG-1 (ATCC 31012) using ethanol or hexadecane as a sole carbon and energy source was performed. In free cell culture, ethanol was more favorable for growth than hexadecane. Most of the emulsification activity was found in the foam collected from the culture. Cells of A, calcoaceticus (RAG-1) were immobilized in Celite R-635, particles of calcined diatomaceous earth. In some experiments Celite particles were coated with alginate layer. In ethanol culture, coating the Celite particles resulted in reduction of the emulsification activity by 20% compared with culture containing the uncoated particles. In hexadecane culture no detectable effect of coating was observed. Immobilization of RAG-1 cells onto Celite particles greatly increased the total emulsification activity of either ethanol or hexadecane culture compared with their free cell cultures.