Sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) was studied as a salt for possible use in sodium-ion batteries. NaTFSI was found to be more thermally stable than NaPF6 in thermogravimetric analysis (TGA) tests. The electrochemical performance of NaTFSI in propylene carbonate (PC) electrolyte was tested using NaCrO2/Na half cells and hard carbon/Na half cells near room temperature. All cells showed equivalent capacity and cycling performance compared to cells using NaClO4/PC electrolyte. The reactivity of deintercalated NaCrO2 (similar to Na0.5CrO2) and sodium-inserted hard carbon (called Na/HC below) in NaTFSI/PC electrolyte was studied using Accelerating Rate Calorimetry (ARC). Na0 5CrO2 shows equivalent reactivity in NaTFSI/PC electrolyte compared to that in NaPF6/EC:DEC electrolyte at elevated temperature. Na/HC shows a lower reactivity in NaTSFI/PC electrolyte compared to NaPF6/EC:DEC and NaClO4/PC electrolytes. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.055304jes] All rights reserved.