The structure of (NH4)(2)B10H10 (1) was determined through powder XRD analysis. The thermal decomposition of 1 and (NH4)(2)B12H12 (2) was examined between 20 and 1000 degrees C using STMBMS methods. Between 200 and 400 degrees C a mixture of NH3 and H-2 evolves from both compounds; above 400 degrees C only H-2 evolves. The dihydrogen bonding interaction in 1 is much stronger than that in 2. The stronger dihydrogen bond in 1 resulted in a significant reduction by up to 60 degrees C, but with a corresponding 25% decrease in the yield of H-2 in the lower temperature region and a doubling of the yield of NH3. The decomposition of 1 follows a lower temperature exothermic reaction pathway that yields substantially more NH3 than the higher temperature endothermic pathway of 2. Heating of 1 at 250 degrees C resulted in partial conversion of B10H102- to B12H122-. Both 1 and 2 form an insoluble polymeric material after decomposition. The elements of the reaction network that control the release of H-2 from the B10H102- can be altered by conducting the experiment under conditions in which pressures of NH3 and H-2 are either near, or away from, their equilibrium values. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.