press as: M. Guerrero, et al., Alkyl sulfonated diphosphines-stabilized ruthenium nanoparticles as efficient nanocatalysts in hydrogenation reactions in biphasic media. Catal. Today Catalysis Today j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a t t o d Alkyl sulfonated diphosphines-stabilized ruthenium nanoparticles as efficient nanocatalysts in hydrogenation reactions in biphasic media a b s t r a c t The organometallic synthesis of ruthenium nanoparticles stabilized by water-soluble alkyl sulfonated diphosphines as ligands is described for the first time. After isolation, the so-obtained nanoparticles could be easily dispersed into water giving rise to stable aqueous colloidal solutions without precipitation over the course of several months. The catalytic behaviour of these aqueous colloidal solutions has been investigated in the hydrogenation of unsaturated substrates (tetradecene, styrene and acetophenone) in biphasic liquid–liquid conditions, showing interesting results in terms of reactivity. Interestingly, small structural differences in the backbone of the diphosphine ligands influence the catalytic activity of these nanocatalysts. In addition, preliminary tests of recycling showed promising results with neither loss of activity or significant precipitation.