Enzymatic biofuel cells (EBFCs) have received much attention in recent years, because they convert energy derived from biofuels to electrical energy by means of the catalytic activity of enzymes (1, 2). As glucose is a ubiquitous fuel in living system the glucose based EFBCs are promising as biocompatible power sources for implantable devices (3). In this study, solid phase interactions and combinatorial approach used for synthesis and covalent attachment of [Ni (phendion) (phen)] Cl2 complex onto carboxyl functionalized multi wall carbon nanotube (MWCNT-COOH) modified glassy carbon electrode. The attached [Ni (phendion) (phen)]Cl2 complex displayed a surface controlled electrode process with electron transfer rate constant and surface coverage 1.96 s-1 and 5.95×10-9 mol.cm-2, respectively, also it acts as an effective redox mediator for electrocatalytic oxidation of NADH at reduced overpotentials. With co-immobilization of glucose dehydrogenase enzyme (GDH) as anodic biocatalyst by crosslinking an effective system for glucose oxidation was designed. The onset potential and current density were -0.1 V versus Ag/AgCl electrode and 0.550 mA cm-2, which indicated the applicability of the proposed system as an efficient bioanode for biofuel cell design. Another integrated system was designed as biocathode using hybrid of MWCNT and electrodeposited gold nanoparticles (Au NP) as a platform for immobilization of bilirubin oxidase (BOD) enzyme on the electrode surface. The as-prepared BOD/MWCNTs/Au NP biocathode exhibited and onset potential of 0.56 V versus Ag/AgCl. The performance of the fabricated bioanode and biocathode in a membraneless enzyme based glucose/O2 biofuel cell (BFC) is further evaluated. The open circuit voltage of the cell and maximum current density were 520 mV and 0.233 mA cm-2, respectively, while maximum power density of 40 μWcm−2 was achieved at voltage of 280 mV. The immobilized enzymes in anode and cathode are very stable and output power of the BF
