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Abstract: Dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) has been successfully performed in supercritical carbon dioxide at P=370bar and T=65°C with azobis(isobutyronitrile) as initiator and a hydrophilic/CO2-philic poly(ethylene oxide)-b-poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) (PEO-b-PFDA) block copolymer as steric stabilizer. The PEO-b-PFDA (2K/21K) block copolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Spherical particles of poly(HEMA) were obtained in the range of 200–400nm diameter size with a narrow particle size distribution (Dw/Dn<1.1). The effect of the stabilizer concentration on the dispersion polymerization was investigated from 20w/w% down to 3.5w/w% versus HEMA. Precipitation polymerization in the absence of stabilizer lead to the formation of large aggregates of partially coalesced particles whereas discrete spherical particles of poly(HEMA) were obtained by dispersion polymerization even at low concentration of PEO-b-PFDA (3.5w/w% versus HEMA). [Copyright &y& Elsevier]