Solid-state decomposition of the dihydrogen-bonded complex LiBH 4 .TEA (TEA: triethanolamine) into a covalent material was probed via 1 1 B MAS NMR and FT-IR spectroscopies, as well as single-crystal and powder X-ray diffraction and optical microscopy. Based on variable-temperature kinetic analysis and H/D exchange experiments, H 2 loss appears to occur via rate-limiting proton transfer from the TEA's OH groups to the BH 4 - anions at the reactant/product interface. The activation parameters ΔH =84+/-10kJ/mol and ΔS =-70+/-26J/(molK) are comparable to those found for neutral aqueous hydrolysis of BH 4 - , suggesting similar mechanisms for the solid and solution decompositions.