NOVELTY - Biocathode comprising an electron conductor; at least one enzyme capable of reacting with a reduced form of an electron mediator and an oxidant to produce an oxidized form of the electron mediator and water; and an enzyme immobilization material comprising an electrocatalyst present in a concentration sufficient to make the enzyme immobilization material conduct electrons, is new.    USE - (I) is useful in the acceptance of electrons from an electrical circuit. (I) is useful in the production of biofuel cell (claimed) for practical electrical applications. The biofuel cell is useful in a variety of pH environments, including physiological environments. The biofuel cell, uses enzymes to catalyze oxidation/reduction reactions instead of metal catalysts.    ADVANTAGE - The invention deals with an improved form of (I) (claimed), which is more stable, highly efficient and less toxic when compared to the conventional biocathodes. The immobilized enzyme of (I) has increased stability.    DETAILED DESCRIPTION - Biocathode (I) comprising:    (a) an electron conductor;    (b) at least one enzyme capable of reacting with a reduced form of an electron mediator and an oxidant to produce an oxidized form of the electron mediator and water; and    (c) an enzyme immobilization material comprising an electrocatalyst present in a concentration sufficient to make the enzyme immobilization material conduct electrons.    The enzyme immobilization material is capable of immobilizing and stabilizing the enzyme. The material is permeable to the oxidant. The oxidized form of the electrocatalyst is capable of gaining electrons from the electron conductor to produce a reduced form of the electrocatalyst that is capable of reacting with an oxidized form of the electron mediator to produce a reduced form of the electron mediator and an oxidized form of the electrocatalyst.    INDEPENDENT CLAIMS are also included for:    (1) a fuel cell comprising a cathode and an anode, where the cathode comprises an electron conductor, a cathode enzyme, an electron transport mediator, and a membrane, where the cathode enzyme is immobilized within a buffered internal compartment of the membrane;    (2) generating electricity using the biofuel cell comprising:    (a) oxidizing the fuel fluid at the anode and reducing the oxidant at the biocathode;    (b) oxidizing the reduced form of the electron mediator during the reduction of the oxidant at the biocathode;    (c) optionally oxidizing the electrocatalyst; and    (d) reducing the electrocatalyst at the electron conductor;    (3) biocathode useful in the acceptance of electrons from an electrical circuit, which comprises an electron conducting material juxtaposed to a dual use membrane, and a dual use membrane, where the dual use membrane comprises a modified ion exchange membrane, an immobilized cathode enzyme and an electron transport mediator;    (4) biofuel cells for generating electricity comprising a fuel fluid, optionally an electron mediator, an anode capable of a reaction to oxidize the fuel fluid and (I); and    (5) generating electrical power, comprising:    (a) oxidizing an organic fuel at an anode in the presence of at least one anode oxidoreductase enzyme, which is incorporated in the anode;    (b) transferring electrons from an oxidized organic fuel to an anode electron conducting material by way of a redox polymer;    (c) reducing an oxygen molecule at a cathode in the presence of an oxygen oxidoreductase enzyme, which is immobilized in a buffered compartment of a modified cathode ion exchange polymer membrane; and    (d) transferring electrons from an electron conducting material to a substrate of the oxygen oxidoreductase by way of an electron transport mediator, which is immobilized in a buffered compartment of a modified ion exchange polymer membrane, such that an electric current is produced.