The electrochemical oxygen reduction reaction (ORR) activity of platinum has been determined in tetraethylammonium hydroxide (TEOH) solution, a solution of imidazole in tetraethylammonium hydroxide, and 1,2,4-triazole in tetraethylammonium hydroxide at elevated temperatures (25 degrees C-80 degrees C). Furthermore, the ORR activity has been compared to that in 12 M KOH. The cyclic voltammetry results as well as the ORR activity measurements suggest a similar activity of platinum in both KOH and TEOH at room temperature. However, the activity in TEOH deteriorates at high temperature due to nucleophilic attack by poorly solvated hydroxide ions. Moreover, addition of either imidazole or triazole has a positive influence on the stability of TEOH at high temperatures, although strong adsorption of both imidazole and triazole significantly inhibits the ORR, resulting in lower activity. Additionally, it is found that the ORR activity of platinum in triazole is superior to that in imidazole. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.037210jes] All rights reserved.