Several endurance tests were carried out to investigate thermal stability of a dye-sensitized solar cell (DSC). In the case of applying an ionic liquid-based electrolyte, no obvious leakage of electrolyte components such as iodine was detected on keeping the cell at 85 degrees C. In addition, double-sealing package was applied to the cell by way of separate cell components from outer moisture. Based on the result, large-sized DSCs with current collecting Ag grid were fabricated, and over 1000 h stability of the cell was accomplished under the heat and humidity environment (85 degrees C, 85% RH). It was also showed almost no degradation of the performance under the heat and cool cycle stress (-40 and 90 degrees C) for more than 200 cycles. (C) 2009 Elsevier B.V. All rights reserved.