Reaction calorimetry is an efficient tool used to obtain kinetic, thermodn., and safety data. A new tool, composed of a high-pressure reactor (HP350) coupled with a Mettler-Toledo RC1e reaction calorimeter, is developed for the investigation of chem. reactions, under supercrit. (s.c.) conditions. The reactor (V = 1.2 L) can be pressurized up to 350 bar and heated to 300 Deg. Results presented in this contribution are divided into three sections. The first part concerns some highlights of the tech. challenge related to supercrit. reaction calorimetry in comparison with the classical liq. calorimetry. The second part presents a Wilson plot anal. with pure supercrit. CO2 and shows that, in contrast to classical liqs., the lower the temp. (above the crit. point) the better the heat transfer coeff. This tendency can be explained by the evolution of scCO2 thermodynamical and transport properties around the crit. point. The third part contains preliminary results from the dispersion polymn. of Me methacrylate in supercrit. carbon dioxide using poly(dimethylsiloxane) macromonomer as stabilizer. Poly(Me methacrylate) can be produced with high yield, high mol. wt., and narrow particle size distribution, using 10 wt% (with respect to monomer) stabilizer under efficient stirring. A polymn. enthalpy of 58.8+-3 kJ/mol has been calcd. with high reproducibility, being in good agreement with previously reported data. This confirms that the employed heat balance model is correct and shows the important potential of reaction calorimetry for the promotion of supercrit. fluid technologies at industrial scale, since it allows the detn. of kinetics, thermodn., and safety data.