Sodium sulfonate-terminated dendritic poly(ester-amine) (SPEA) was synthesized by sulfonation of acrylic double bond-terminated dendritic poly(ester-amine) (APEA) with sodium hydrogen sulfite (NaHSO3) in mixture of diglycol and 2-butanone under normal pressure. The structure of SPEA was characterized by IR, H-1-NMR, and elemental analysis. SPEA was water-soluble. 1.0-40.0% (mass) SPEA aqueous solutions appeared as dilatant fluid. When pH value varied from 1.5 to 12.0, the viscosity of 1-5% (mass) SPEA aqueous solutions changed very small, and the electric conductivity almost kept stable within pH 3.0-10.0. The relationship between the viscosity and the concentration of SPEA water solutions was similar to that of NaCl water solutions. The surface tension of SPEA water solutions was lower than that of polyethylene glycol 2000 water solutions with the same concentration. (c) 2007 Wiley Periodicals, Inc.