New sulfonated naphthylphosphanes having an average sulfonation degree around 2 have been synthetized and tested as ligand in the aqueous biphasic Rh-catalyzed hydroformylation of 1-decene assisted by randomly methylated p-cyclodextrins. All these water-soluble phosphanes associated to a rhodium precursor were able to perform aqueous hydroformylation of 1-decene. The best results in terms of catalyst recovery and recycling were obtained with sulfonated 2-naphthylphosphanes. With sulfonated 1-naphthylphosphanes, formation of low-coordinated catalytic species leading to a catalyst leaching in the organic phase was postulated. These results were rationalized by considering that sulfonated 1-naphthylphosphanes are bulkier ligands than sulfonated 2-naphthylphosphanes. (C) 2014 Elsevier B.V. All rights reserved.