Abstract: A method for potentiometric detection of hydrogen peroxide including providing an electrolytic cell having a working electrode and a reference electrode. The working electrode is composed of a hydrogen peroxide sensitive material and also is employed as a support for an oxidase enzyme. Introducing a hydrogen peroxide releasing substance into the cell and releasing the hydrogen peroxide by effecting interaction with the enzyme. Developing in said cell an electrical potential which is a function of the concentration of the hydrogen peroxide and measuring the electrical potential of the cell. The method may be employed as a quantitative glucose detector by employing as the enzyme or enzymes glucose oxidase with or without catalase.Apparatus for potentiometric determination of hydrogen peroxide includes a cell containing an electrolyte, a working electrode and a reference electrode. An electrometer is operatively associated with the electrodes.