The second order nonlinear optical (NLO) properties of various simple tris-cyclometallated Ir(III) complexes bearing 2-phenylpyridine ligands have been investigated by means of the EFISH technique, evidencing how appropriate substitution of the cyclometallated ligands may allow the tuning of the second-order NLO response of this unusual family of 3D chromophores. To evaluate the dipole moments and to gain insight into the electronic structure and optical properties of the investigated complexes we also performed Density Functional Theory (DFT) calculations.