Currently, there is a renewed interest in biofuel cells. At the same time, recent advances in nanoscale science and technology are fueling a new wave of revitalization in the field of biocatalysts. Nanoscale engineering of the biocatalysts is greatly promising for the development of high performance biofuel cells. Glucose oxidase electrodes were prepared via forming composites with carbon fibers, carbon nanotubes, and nanoporous carbon materials. Significant enhancement on electrochemical flux and reaction kinetics was observed on the composite-modified glassy carbon electrode by cyclic voltammetry. When the resulting electrodes were applied in a model glucose/O2 biofuel cell as the anodes, a power density up to about 900 μw/sq cm was achieved. According to the quantitative analysis of the processes involved in the anode, mass transfer of the mediator was the limiting factor to the power and current densities of the model biofuel cell. This is an abstract of a paper presented at the 2005 AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).