An amperometric sol-gel-derived biosensor for the detection of hydrogen peroxide was constructed by immobilizing horseradish peroxidase(HRP) and an osmium redox polymer([Os(bpy)2(PVP)10Cl]Cl; abbreviated Os-polymer) as mediator. Upon addition of hydrogen peroxide to the solution, a bioelectrocatalytic reduction current wave was observed. The steady-state hydrogen peroxide catalytic reduction current reached a plateau at 150 mV vs, Ag/AgCl and hydrogen peroxide could be determined amperometrically with good sensitivity at -50 mV vs. Ag/AgCl. This biosensor exhibits a rapid response(t(95%)=10 s) on addition of 1.0 mM hydrogen peroxide. The linear response range, apparent Michaelis-Menten constant(Km'), and detection limit were 0.01 ∼ 2.7 mM, 5.93 mM, and 0.005 mM, respectively. Uric acid, dopamine, ascorbic acid, paracetamol were found not to interfere at this potentials. The biosensor was found to be stable for 1 month on storage at 4°C.