Two types of amphiphilic block copolymer; poly(2-hydroxyethyl vinyl ether)-block-poly[2-(2,2,2-trifluoroethoxy)ethyl vinyl ether] (poly(HOVE-b-TFEOVE)) (m:n = 78:23) and poly(2-hydroxyethyl vinyl ether)-block-poly(n-butyl vinyl ether) (poly(HOVE-b-NBVE)) (m:n = 74:23), having the same ratios of polymerization degree in hydrophilic and hydrophobic segments with the same total chain length were synthesized, and the properties of their aqueous solutions were investigated, where m and n represent number-averaged polymerization degree of HOVE and TFEOVE or NBVE, respectively. By water surface tension measurements, the critical micelle concentrations (cmc's) of poly(HOVE-b-TFEOVE) and poly(HOVE-b-NBVE) were both estimated at 1.0 x 10(-4) mol/L. Solubilization of various fluoro and non-fluoro compounds using these polymer aqueous solutions was examined. It was confirmed that poly(HOVE-b-TFEOVE) solubilized more decafluorobiphenyl than did poly(HOVE-b-NBVE), whereas poly(HOVE-b-NBVE) solubilized more 2,6-dimethylnaphthalene than did poly(HOVE-b-TFEOVE). When a mixture of decafluorobiphenyl and 2,6-dimethylnaphthalene was added to the polymer: solutions, poly(HOVE-b-TFEOVE) selectively solubilized decafluorobiphenyl, while poly(HOVE-b-NBVE) solubilized 2,6-dimethylnaphthalene predominantly, which was observed by the UV absorption spectrum of the polymer solutions.