In the present report we focused on the substitution of metallic catalysts by biocatalysts to develop a high efficient biofuel cell. A bioanode and a biocathode were designed using ADH and laccase, respectively. Carboxylated multiwall carbon nanotubes (HOOC-MWCNTs) and polydiallyldimethylammonium chloride (PDDA) were used for immobilizing the enzymes on either polymethylene green (PMG) modified glassy carbon or graphite electrodes. In this way, an ethanol-oxygen biofuel cell was designed in which PDDA/ADH/PDDA/HOOC-MWCNTs/PMG/GC and PDDA/Lac/PDDA/HOOC-MWCNTs/PMG/Gr operated as bioanode and biocathode, respectively. In the optimized condition of O-2 saturated PBS (0.1 M, pH 7.5) containing 1 mM ethanol and 1 mM NAD(+) the open-circuit voltage reached to a plateau at 504 mV based of which the power density of 3.98 mW cm(-2) was obtained. (C) 2016 Published by Elsevier Inc.