The [PdCl2(NH2(CH2)(12)CH3)(2)] complex supported on gamma-Al2O3 has proved to be a considerably more active, selective and sulfur-resistant catalyst in the selective hydrogenation of styrene to ethylbenzene than a traditional catalyst obtained from acid solutions of PdCl2, and even than the same complex unsupported. The active species is the complex itself and it is stable under the reaction conditions. Hydrogen treatments above 353 K destroy the complex, at least partially, leading to a less active and sulfur resistant catalyst. The higher sulfur resistance, when compared to a conventional Pd/Al2O3 catalyst, can be attributed to electronic and geometrical effects.