A quinohemoprotein alcohol dehydrogenase (QH-EDH) from Comamonas testosteroni was immobilized on an electrode in a redox polymer network consisting of a polyvinylpyridine partially N-complexed with osmiumbis-(bipyridine)chloride. The enzyme effectively transfers electrons to the electrode via the polymer. An average maximum catalytic current of 11 mu A cm(-2) was observed with 1-propanol as the substrate. The maximum activity of the enzyme electrode (current density) for primary alcohols is independent of the type of substrate in contrast with the activity of the free enzyme. Affinity constants of the immobilized QH-EDH for different substrates are comparable with the values found for the free enzyme. Typical half-lives for the immobilized enzyme electrodes are in the order of 5 h.