BaMoO 3 , metallic and Pauli paramagnetic, has been prepared by controlled reduction of BaMoO 4 . This precursor, containing Mo(VI), is unusually stable against reduction, due to structural factors. The crystal structure of BaMoO 4 has been refined from neutron powder diffraction data: space group I4 1 /a (no. 88), Z=4, a=5.5479(9), and c=12.743(2) Å. A bond-valence study allowed us to detect the presence of slight tensile and compressive stresses in the crystal structure of BaMoO 4 , in which Ba is overbonded and Mo is underbonded. However, this effect is less pronounced than in other AMO 4 oxides with a scheelite structure (A=Ca, Sr, Ba; M=Mo, W): BaMoO 4 contains the M cation exhibiting the closest valence to the nominal value of 6+, suggesting a large covalent contribution to the Mo–O bonds. This observation is coherent with the large thermal stability of this compound against reduction, taking place at temperatures above 920°C in H 2 flow.