Abstract We have computed and compared the geometries, the electronic properties and reactivity sites of a set of Alq3‐derivatives (5AP‐Mq3, M=Al, Ga, In) with potential use in organic light emitting diodes (OLED), using electronic and chemical reactivity descriptors. All the geometries were optimized with the ab initio Hartree‐Fock (HF) method and the 3‐21G basis set and the different descriptors were calculated at a B3LYP/3‐21G level of theory. The results show that the geometric structures were all distorted octahedral, where the geometrical parameters increase in the order 5AP‐Alq3 < 5AP‐Gaq3 < 5AP‐Inq3. The frontier molecular orbitals HOMO and LUMO are split in energy and strongly localized in a specific region of the ligands. The reactivity analysis shows that the atoms that receive electrons are those associated with the lowest unoccupied molecular orbital, LUMO.