The hydrolysis and the redox process of the water soluble system dppp-s/Pd-[] has been investigated at room temperature by P-31 NMR spectroscopy, polarography and potentiometry {dppp-s = sodium salt of 1,3-bis(dimetasulfophenylphosphino) propane}. In dilute solution [palladium salt] = 3.3 x 10(-4) mol/l (molar ratio dppp-s/P-[], R = 1), contrary to the TPPTS/Pd-[] system, the complex Pd(dppp-s)(2+) was hydrolyzed without phosphine oxidation, keeping a surprising stability up to pH = 9 or 10. Above pH = 10, the bidentate phosphine is oxidized. The hydrolysis and the reduction reactions are linked to the palladium salt concentration. In more concentrated solutions, the hydrolysis reaction and the phosphine oxidation occurs at lower pH (pH = 4). The hypothesis of the binuclear complex formation {[(dppp-s)Pd(H2O)][(dppp-s)Pd(OH)]}(3+) or [(dppp-s)Pd(mu-OH)(2)Pd(dppp-s)](2+) was proposed. An excess of phosphine restricts the redox and the hydrolysis reactions (pH < 10; R = 2). In this case, four phosphorus atoms are bounded to Pd-[](delta = 3.1 ppm) and prevents the complete hydrolysis. The stability of the system dppp-s/Pd-[] is dictated by the pH value, the molar ratio dppp-s/Pd-[] and the dilution. (C) 2002 Elsevier Science B.V. All rights reserved.