Gaseous absorption measurements of hydrofluorocarbons (trifluoromethane, difluoromethane, pentafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1-trifluoroethane, and 1,1-difluoroethane) in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were performed using a gravimetric microbalance at various isothermal conditions (temperatures between 283.15 and 348.15 K) and at pressures < 2 MPa. This report shows for the first time the solubility and diffusivity data for the hydrofluorocarbons in room-temperature ionic liquids and surprisingly large differences in the solubility among the hydrofluorocarbons. Experimental gas solubility data were successfully correlated with well-known solution models (Margules, Wilson, and NRTL activity coefficient equations). Diffusivities obtained from the time-dependent absorption data were well analyzed using a diffusivity model developed in this study. The present solubility and diffusivity data are also compared with those Of CO2, studied in our previous study. (c) 2005 American Institute of Chemical Engineers.