Technical Abstract: Amperometric sensors containing immobilized cells of Gluconobacter oxydans were hyperoxygenated to 400% of control levels and the effects determined on sensor responses to glucose. Oxygenated perfluorodecaline (a completely fluorinated organic substance) was as effective in hyperoxygenation as direct sparging with O2, increasing sensor base medium oxygen concentrations from 9.3 to 37 mg/l. Hyperoxygenation enhanced maximal biosensor response amplitudes, particularly at high cell loading densities. Maximal response rates were also improved, although less dramatically. Results suggest that hyperoxygenation may be a new general approach for modulating biosensor responses.