A fluorinated analogue of the hydroformylation catalyst, HRh(CO)(PPh3)(3) was synthesized for hydroformylation of olefins in supercritical carbon dioxide (scCO(2)). The catalyst, HRh(CO)[P(3,5-(CF3)(2)C6H3)(3)](3), was found to bean extremely active catalyst in scCO(2) for hydroformylation of 1-octene with maximum TOFs around 15 000 h(-1) at a relatively mild temperature of 65 degrees C. The very high activity results from the low basicity of the ligand. The kinetics of hydroformylation of 1-octene in scCO(2) with the catalyst was investigated. The results were successfully interpreted using the generally accepted catalytic cycle in the literature based on a dissociative mechanism. The reaction is nearly first order with respect to H-2, which suggests that oxidative addition of hydrogen to an acyl intermediate is the rate-determining step in scCO(2) at the low phosphine concentrations employed. The commonly observed decrease in reaction rate with increasing phosphine concentration with HRh(CO)(PPh3)(3) in conventional solvents was not observed due to the low basicity of the ligand.