All-solid-state flexible supercapacitor is assembled using multi-walled carbon nanotubes (MWCNT) and ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] based gel polymer electrolyte. Flexible electrodes on polyethylene-terephthalate (PET) substrate were made by inkjet printed azide functionalized MWCNT (f-MWCNT), serving both as electrodes and charge collector. Fabricated supercapacitor f-MWCNT/gel polymer electrolyte/f-MWCNT (f-MWCNT SC) demonstrated high power and energy performance as a gel polymer electrolyte based all solid-state flexible supercapacitor. f-MWCNT SC demonstrates high specific capacitance 235 Fig at 5 mV/s in wide operating potential range of 3 V. Short relaxation time constant (tau(o)) (248 ms) with high apparent diffusion coefficient (D-a) 2.25 x 10(-8) cm(2)/s resulted in very high energy density 16.2 Wh/kg and power density 45 kW/kg at 1 A/g.f-MWCNT SC exhibits high flexibility and excellent cycling stability with capacity retention >90% after 5000 galvanostatic charge discharge cycles. (C) 2016 Elsevier Ltd. All rights reserved.