An integrated device of enzymatic biofuel cells (EBFCs) and supercapacitor (SC) on glass or flexible polyethylene terephthalate for both electric energy conversion and storage has been developed. A glucose/O-2 EBFC was fabricated by modifying flavin adenine dinucleotide-glucose dehydrogenase and laccase on multi-walled carbon nanotubes (MWNTs) based buckypaper as bioanode and biocathode, respectively. While the SC was fabricated by sandwiching a poly(vinyl alcohol)-H3PO4 (PVA-H3PO4) electrolyte between two aligned MWNTs/polyaniline electrodes. The integrated device showed lower internal resistance than previous report because of the use of solid state electrolyte PVA-H3PO4. Furthermore, the self-charged device containing two EBFCs and one SC achieved a high charging voltage of 0.8 V and a maximum power density of 608 mu W cm(-2), which was 1.9 times of that value for two individual EBFCs in series (326 +/- 10 mW cm(-2)). Such a miniaturized device with a light weight and flexible property would enable new opportunity for portable and wearable devices. (C) 2017 Elsevier Ltd. All rights reserved.