An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modi-fication of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H2O2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of pH, potential and temperature. A remarkable feature of the biosensor is the detection of H2O2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response (2 s). The biosensor showed a linear range from 15 nM to 45 mM of H2O2 and a detection limit of 5 nM. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility, stability and analytical performance of the sensor are very good.