The stability of gaseous BMoO₄ was confirmed by Knudsen effusion mass spectrometry. The gas-phase reaction involving B₂O₃, MoO₂, MoO₃ and BMoO₄ was studied. On the basis of the equilibrium constants, the standard formation and atomization enthalpies of gaseous BMoO₄ (−744.1 ± 24 kJ mol⁻¹ and 2963 ± 25 kJ mol⁻¹, respectively) at 298 K were determined. To obtain the structure parameters and vibrational frequencies of gaseous BMoO₄, a quantum chemical investigation of this molecule was undertaken. Based on the critical analysis of the literature data concerning the standard formation enthalpies of gaseous BWO₄, BPO₄ and BPO₃, we adopted new values for Δ_f H ⁰(298) which are equal (−934.4 ± 29.3 kJ mol⁻¹, −975.8 ± 16.2 kJ mol⁻¹ and −717.0 ± 19.3 kJ mol⁻¹), respectively.