Dissolved oxygen is known to promote stress corrosion cracking of carbon steel in fuel grade ethanol (FGE). It is of interest to perform corrosion and stress corrosion cracking studies in deaerated simulated fuel grade ethanol (SFGE) under controlled potential conditions to understand the effect of dissolved oxygen. However, accurate potential control in SFGE requires a suitable supporting electrolyte. The effects of adding different supporting electrolyte salts on electrochemical properties and cracking tendency of carbon steel in deaerated SFGE were investigated. Control experiments in SFGE without supporting electrolyte were performed using the microelectrode technique, which minimizes the ohmic potential drop. Among all the tested inorganic lithium and organic tetraalkylammonium salts, tetrabutylammonium tetrafluoroborate (TBA-TFB), was determined to be a suitable supporting electrolyte for deaerated SFGE. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.002302jes] All rights reserved.