Styrene-methyl methacrylate-glycidyl methacrylate terpolymers to be used as binders in powder coating materials were synthesized in a homogeneous fluid phase containing 20 wt % CO2. Reactions carried out at 120 degreesC and 350 bar yield almost complete monomer conversion. The molecular weights were around 3000 g.mol(-1) with a polydispersity index of 1.7. Molecular weight control was achieved by n-dodecyl mercaptan or by a catalytic chain-transfer agent. Simulations of the cumulative and differential copolymer composition are in excellent agreement with experimentally derived values.