Thermal decomposition of monochlorogallane, [H2GaCl](n), at ambient temperatures releases H-2 and results in the formation of gallium(I) species, including the new compound Ga[GaHCl3], which has been characterized crystallographic ally at 100 K (monoclinic P2(1)/n, a = 5.730(1), b = 6.787(1), c = 14.508(1) Angstrom, beta = 97.902(5)degrees) and by its Raman spectrum. The gallane suffers symmetrical cleavage of the Ga(mu -Cl)(2)Ga bridge in its reaction with NMe3 but unsymmetrical cleavage, giving [H2Ga(NH3)(2)]Cl-+(-), in its reaction with NH3. Ethene inserts into the Ga-H bonds to form first [Et(H)GaCl](2) and then [Et2GaCl](2).