The use of XRD and DTA methods has allowed studies on the interaction of the SbVO5 and MoO3, taking place in the solid state and in the medium of ambient air. The experimental results of XRD and DTA for all the samples
showed the presence of a novel phase, i.e. Sb3V2Mo3O21 apart from various amounts of MoO3 and V9Mo6O40 or SbVO5 and V2O5(s.s.). The SbVO5–MoO3 system is not a real two-component system over the entire range of component concentrations up to the solidus line.