Solid-state electrochemical double-layer capacitors (ELDCs) based on alkaline polyvinyl alcohol (PVA) solid polymer electrolytes (SPEs) are prepared. Electrochemical capacitance performance of these capacitors is studied by cyclic voltammetry, galvanostatic charge–discharge testing, and ac impedance spectroscopy. For comparison, two types of EDLC cells are constructed and tested. It is found that an EDLC with a PVA polymer electrolyte exhibits much higher capacitance and longer cycle-life than one with the PP/PE separator. The specific capacitance for the EDLC with the PVA-based SPE is in the range of 100–112Fg−1, and depends on the scan rate or the charge–discharge current rates. The results also indicate that the solid-state EDLC shows a relatively stable specific capacitance of 100Fg−1 after 1000 cycles. The findings suggest that the PVA-based SPE is a promising material for use in EDLCs.