An all solid-state electrochemical capacitor operated in the temperature range of 150-180 degreesC was fabricated with MnO2 thin film electrode and CsHSO4 proton-conductive electrolyte. The sample has a cell structure of Au/MnO2/CsHSO4/MnO2/Au. The electrochemical behavior of the capacitor was characterized by cyclic voltammetry technique. It was found that such electrochemical capacitor exhibited a typical cyclic voltammogram of electrochemical capacitors with the average capacity of 1.30 x 10(2) F g(-1) (at 180 degreesC) and showed a significant increase of the capacity by elevating the operation temperature. This result can be explained by the enhancement of proton diffusion into the MnO2 electrode. (C) 2004 Elsevier B.V. All rights reserved.