If carbon sequestration approaches that employ biological methods are to be made viable for the capture of carbon from fossil fuel combustion waste gas streams, a separation technique that is both economically and environmentally green is needed. One concern is the potential negative consequences of certain gases, such as sulfur dioxide, on aqueous-based sequestration approaches. This study experimentally determined the ability of room-temperature ionic liquids and ionic liquid-based mixtures to absorb combustion-related acid gases, carbon dioxide and sulfur dioxide, from gas streams. Ionic liquids are novel organic salts that are liquids at or near room temperature. These solvents have a negligible vapor pressure, and have been called green “designer” solvents due to the vast number of anion-cation combinations that are possible. This work has directly measured the uptake of target gases by the ionic liquid utilizing a quartz-crystal microbalance (QCM), a technique that has demonstrated sensitivity on the nanogram scale. The acid gases studied in this experiment were tested on a selection of ionic liquids of the alkyl-imidazolium family as well as mixtures containing ionic liquids. 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [hmim][Tf2N], was used as a benchmark due to the presence of accepted literature data for certain of the above acid gases. Additionally, special attention will be paid to the variation of results with respect to ionic liquids structural and functional selection. New developments will also be discussed.