RuCl2(TPPMS)(3)(DMSO) (complex I) shows good catalytic 1-hexene hydrogenation activity in toluene/water biphasic medium under moderate conditions, reaching 90% conversion in 5 h, with good hydrogenation selectivity and low isomerization products. The effect of various parameters (temperature, H, pressure, reaction time, substrate/catalyst ratio, added electrolytes and other additives) on the hydrogenation reaction were studied. Complex (1) shows good stability in the reaction medium and can be reused several times.