The use of differential thermal analysis (DTA) and X-ray diffraction (XRD) methods has enabled studies on the behaviour of Al-2(MoO4)(3) towards V2O5 in the solid state over the whole component concentration range. The experimental results are presented in the form of a phase diagram. The Al-2(MoO4)(3)-V2O5 system is not a real bicomponent system, being only a vertical intersection of the tricomponent system, Al2O3-V2O5-MoO3.