The complex [RhCl(NH2(CH2)(12)CH3)(3)] was tested for the semihydrogenation of 1-heptyne in homogeneous and heterogeneous conditions. gamma-Al2O3 and two different commercial activated carbons (RX-3 EXTRA and GF-45) were used as supports. The results were, then, compared with those previously reported for the [PdCl2(NH2(CH2)(12)CH3)(2)] complex supported or unsupported, and with the results obtained with the classic Lindlar catalyst. The complex was characterised by FTIR and elemental analysis. The pure species and the supported one were also characterised by X-ray photoelectron spectroscopy. Results determined by the latter technique suggest that the active species is the complex itself, which is stable under the reaction conditions. The supported rhodium tetra-coordinated complex shows higher activity and selectivity than the same complex unsupported, and also than the classic Lindlar catalyst. Moreover, among the rhodium-supported complexes the one immobilised on RX-3 EXTRA has a better performance than that heterogenised on GF-45, and this one has a better activity and selectivity than the gamma-Al2O3 anchored complex. Our results also show that under the same operational conditions (temperature, hydrogen pressure and metal/substrate weight ratio) the rhodium complex, unsupported or supported, has a better performance than the corresponding palladium complex. (C) 2004 Society of Chemical Industry.