The paper reports infinite dilution activity coefficients of a series of polar and nonpolar solutes (alkanes, alcohols, ketones, ethers, aromatic hydrocarbons, halogenated compounds) in 1-butyl-3-methylimidazolium nitrate and 1,1-hydroxypropyl-3-methylimidazolium nitrate ionic liquids at (323, 333, and 343) K. The data were measured by gas-liquid chromatography using the ionic liquid as a stationary phase.