The decomposition of aluminum hydride complexes with trimethylamine and N-heterocyclic carbene—1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene was studied by a static tensimetric method with a membrane null-manometer. The AlH3·NMe3 complex passes into vapor in the form of monomeric molecules and in unsaturated vapor slowly decomposes at 70‒80°С into solid aluminum, gaseous trimethylamine, and hydrogen. The decomposition is accompanied by an induction period, the duration of which decreases as temperature increases. The AlH3 complex with carbene slowly decomposes at 170‒200°С with a rate practically independent of temperature.