The physicochemical characteristics of two homologous room temperature ionic liquids (RTIL, IL) 1-methyl-1-propylpyrrolidinium bis[(trifluoromethyl) sulfonyl] imide [MPPyr][NTf2] and 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl) sulfonyl] imide [BMPyr][NTf2] are presented. Based on density, speed of sound, viscosity and surface tension measured in the temperature range of (288.15 to 323.15) K some related parameters, like isobaric coefficient of thermal expansion, isentropic compressibility coefficient, parameters of Vogel-Fulcher-Tamman (VFT) equation, surface entropy and enthalpy were calculated. These results were compared with those of some homologs from the 1-alkyl-3-methyl imidazolium bis[(trifluoromethyl) sulfonyl] imide [C(n)MIm][NTf2] family in order to systematize the knowledge about investigated substances. In the next part volumetric and surface properties, like excess molar volumes and Gibbs surface excess of methanol or acetonitrile in binary systems with [BMPyr][NTf2] were determined at three temperatures (288.15, 298.15 and 308.15) K. The results of these studies indicate that the volumetric quantities of binary mixtures and the surface properties obtained with same solvents in two different classes of ionic liquids pyrrolidinium bis[(trifluoromethyl) sulfonyl] imides and imidazolium bis[(trifluoromethyl) sulfonyl] imides are very similar. (C) 2013 Elsevier Ltd. All rights reserved.