in Wiley InterScience (www.interscience.wiley.com).Molecular dynamics simulations have been carried out on CO 2 -[bmim] [PF 6 ] mixtures using a refined atomistic potential model for the ionic liquid, at different concentrations of CO 2 . The expansion in volume as a function of added CO 2 was found to agree well with experiments at all but the highest concentration. Significant concentration dependent differences in the radial distribution function of CO 2 around the anion have been observed. These differences have been attributed to the specific interaction between CO 2 and the anions. The diffusion coefficients of the ions and of CO 2 have been found to increase with increase in CO 2 concentration. The rotational relaxation of CO 2 molecule in solution is found to be biexponential, and the mean relaxation times decreases with increasing CO 2 concentration.