A number of gaseous oxyacid salts have been identified by Knudsen effusion mass spectrometry by vaporizing Ga₂O₃ from molybdenum and tungsten cells. The stability of gaseous molecules Ga₂MoO ₄, Ga₂WO₄, Ga₂Mo2O₇, and Ga2W2O7 was deduced from the measurements. The structures and molecular parameters of all salts investigated were obtained using quantum chemical calculations. On the basis of equilibrium constants measured for gas-phase reactions, the standard formation enthalpies were determined to be-827 ± 26,-843 ± 26,-1578 ± 32, and-1525 ± 34 kJ · mol-1 for Ga₂MoO₄, Ga₂ WO₂, Ga₂ Mo2O₇, and Ga₂W2O₇, respectively.