Abstract The effect of Nb, V, Cr and Mn on the lattice parameters of γ-TiAl and the site preference of these transition metals were studied based on first-principles supercell calculations of the electronic structure and total energy of ordered Ti n − 1 XAl n and Ti n XAl n − 1 compounds with X = Nb, V, Cr and Mn. For the calculation of optimized volumes by total energy minimization 4-, 8- and 32-atom cells were taken into account. Trends of c a changes in connection with the analysis of the electronic structure are derived from 4-atom supercell results in continuation of a previously published Part 1 of our investigations. We find that Mn has the strongest preference for Al sites because of strong stabilizing electronic structure effects. The substantial decreased value of the c a ratio found for the case of Mn substituting for Al is related to a bcc-like local arrangement of Ti around the Mn atom. This geometrical situation is accompanied by the formation of a deep pseudogap in the density of states. The Fermi energy falls precisely into this pseudogap which distinctly separates TiMn bonding and antibonding states. The site preference trend for the other substitutional compounds containing X = Nb, V, Cr are also discussed in combination with their corresponding density of states.