Quinohaemoprotein alcohol dehydrogenase from Comamonas testosteroni(QH-EDH) was immobilised in a redox polymer network of a polyvinylpyridine, partially N-complexed with osmiumbis(bipyridine)chloride. Substrate-dependent electron transfer occurred, indicating that the enzyme was active and that effective electron transport was achieved. It was shown that the enzyme molecular weight is of importance with respect to the enzyme electrode stability. Long term stability and current density of the th QH-EDH electrodes were highest when the enzyme was immobilised at pH 10.0 and 4 degrees C, followed by an additional cross-linking step with glutaraldehyde (1%) at ph 7.0. With such an electrode current densities of 40 mu A cm(-2) were obtained for several primary alcohols. The affinity of the immoblised enzyme for these substrates (K-m(app) values) was similar to that of the enzyme in solution. The half-life time of the electrodes was between 50 h and 200 h depending on the time the enzyme was in contact with the substrate. When the immobilised enzyme electrode was operated at temperatures above 37 degrees C the stability decreased.