The viscosities of the ionic liqs. [bmim][PF6] and [bmim][TF2N] (bmim = 1-methyl-3-butylimidazolium, TF2N = bis(trifluoromethylsulfonyl)imide) have been detd. under CO2 pressure at 298 K. The viscosity decreases from 381 to 23 cP for [bmim][PF6] without CO2 and for 2.17 m CO2 solns. (mole fraction XCO2 = 0.381, 55 bar CO2), resp. For [bmim][TF2N] the viscosity decreases from 54 cP for the ionic liq. to 21 cP for a 1.61 m soln. of CO2 (mole fraction XCO2 = 0.403, 55 bar CO2).