The presence of Mg 2+ - and Fe 3+ -ions has an effect on the formation of Al 2 TiO 5 . Crystalline phases produced under the influence of the heat treatment have been identified in a heated X-ray diffraction chamber in the temperature range of 20–1500°C. In the presence of Mg 2+ - and Fe 3+ -ions transitional phases are formed in the temperature range of 1000–1350°C during Al 2 TiO 5 formation. The XRD technique was used to identify the crystalline phases formed. On addition of MgO, chemical composition of the transitional phase formed is Mg 0.3 Al 1.4 Ti 1.3 O 5 , whereas on addition of Fe 2 O 3 we have calculated a Powder Diffraction File card data for the transitional phase. Determination of the lattice parameters of the Al 2 TiO 5 ceramics produced enabled verification of incorporation of Mg 2+ - or Fe 3+ -ions into the crystal lattice of Al 2 TiO 5 , i.e. the formation of Mg 2+ - and Fe 3+ -containing solid solutions.