Pichia methanolica and Gluconobacter oxydans were immobilized on chromatographic paper and fixed on an Clark type oxygen electrode. The lower limit of ethanol detection was 0.05 mM for both types of biosensors. Of all substrates tested (ethanol, methanol, isopropanol, glucose, xylose, xylitol, arabinose, arabitol, glycerol, pyruvate, citrate, acetate), the P. methanolica-based sensor had a higher selectivity and was susceptible only to ethanol, methanol and insignificantly to isopropanol. The sensor based on G. oxydans cells was less selective. The major interfering compounds were glucose and glycerol. The dependence of signal amplitude on the conditions of measurement and cell density was studied in both sensor models. The sensors proved reasonably stable and after 8 days of continuous measurements the signal decreased not more than 50% for both types of biosensors.