Polysilanes having oxyethylenic side chains, {CH3-Si-CH2CH2CH2O(CH2CH2O)(m)R(1)}, where (m = 0,1,2,3) and R(1) = CH3 and C2H5, have been prepared. A polysilane of m = 3 and R = CH3 is soluble in alcohols, acetonitrile, and water. Surface tensions of these polysilanes are larger than those of the polysilanes ever reported. While dispersion component stays almost constant (ca. 30-40 dyn/cm), polar component increases with increasing oxygen atom numbers in the side chain. Copolymers also keep the high values of surface tension.