Abstract: An electrical signal can induce a biological reaction; the reverse in is also true in most of the cases and in this way biological processes can be used to generate electricity for powering electrical equipment. Even though the Bio fuel cells have been known for almost a century since the first microbial BFC(Bio fuel cells) was demonstrated in 1912,the first enzyme-based bio-fuel cell was reported only in 1964 using glucose oxidize (GOx) as the anodic catalyst and glucose as the bio-fuel. a type of battery that uses energy sources such as carbohydrates, amino acids and enzymes from a variety of sources. anode consists of sugar-digesting enzymes and mediator, and the cathode composes of oxygen reducing enzymes and mediator. The mediators in this case are Vitamin K3 for the anode and potassium ferricyanide for the cathode. When sugar is added to the mixture, the anode garners the electrons and hydrogen ions. When the battery generates power, the protons travel to the cathode through the electrolyte to combine with the oxygen to produce water. Since the biocatalysts (enzymes) are very selective catalytically, the miniaturized bio-fuel cell could in principle be fabricated as a membrane-less fuel cell. Keywords: Bio-fuel Cells, Biocatalyst, Glucose Oxides, Enzymes.