A solar thermal cell is composed of the chemical reaction of 2-propanol/acetone/hydrogen and a fuel cell. We have examined the influence of the internal structure and the temperature in the solar thermal cell on the output of the cell. As the main results, (1) with increasing the temperature of the positive electrode, the short circuit current of the cell has increased, (2) with decreasing the thickness of the electrode space, the output of the cell has increased and (3) under the condition that the electrodes are kept in good contact with the polymer electrolyte, the performance of the cell increases and the short circuit current reaches 80 mA. (C) 2003 Elsevier Science Ltd. All rights reserved.