Gel polymer electrolytes consisted of polyvinylpyrrolidone (PVP) and PVP-polyvinylacetate (PVP-PVAc) as base polymers, (C2H5)(4)NBF4 as an electrolyte salt and propylene carbonate (PC) as a plasticizer. The electric conductance of the gel polymer electrolytes, the capacitance and charge-discharge current efficiency of test capacitors with these electrolytes and activated carbon fiber were measured. The conductivity of the gel polymer electrolytes was measured in the range between -20 and +60 degrees C, and was around 10(-3) S cm(-1) at 25 degrees C. The discharge capacitance of one of the electrode of model capacitors with PVP-PVAc-based polymer was 0.74 F cm(-2) (38 F g(-1)), and cycling current efficiency was over 90%.