The hydroformylation of 1-dodecene catalyzed by RhCl(CO)(TPPTS)(2)-BISBIS [TPPTS: P(m-C6H4SO3Na)(3), BISBIS: sulfonated 1, 1'-bis(diphenylphosphino methyl)-2,2'-biphenyl] in aqueous/organic two-phase system was studied. The addition of cationic surfactant cetyltrimethylamonium bromide (CTAB) greatly accelerated the reaction rate and the high regioselictivity for linear aldehyde using diphosphine as ligand was attained under two-phase conditions. Both high activity (TOF: 740 h(-1)) and excellent regioselectivity (96.5% of 1-tridecanal) were obtained at 120 degreesC, 2.0 MPa and [BISBIS]/[Rh] ratio of 3 in the presence of CTAB. (C) 2002 Elsevier Science B.V All rights reserved.