- During the investigations on the Al-rich corner of the Th–T–Al system (where T = Ti, V, Mn), new intermetallic phases were revealed: ternary ThV 2 Al 20 , ThTi 2 Al 20 , ThMn 2 Al 10 and pseudo-binary Th 3 Al 11 (containing traces of vanadium). Their structure was investigated by means of Transmission Electron Microscopy and powder X-ray diffraction methods. Refinement of these structures was performed applying Rietveld analysis on X-ray diffraction data. It was established that ThV 2 Al 20 and ThTi 2 Al 20 phases can be ascribed to the CeCr 2 Al 20 structure type, while ThMn 2 Al 10 possesses the YbFe 2 Al 10 -type structure. The pseudo-binary (Th 1 − x V x ) 3 Al 11 phase was found to be orthorhombic ( Immm ; a = 4.4354(8) A, b = 13.8394(9) A and c = 10.3486(5) A), isostructural to La 3 Al 11 . It was proposed that metastable Th 3 Al 11 phase can be stabilized by small amount of vanadium, which was found in its content.