Several physical properties were determined for the ionic liquids 3-methyl-N-butylpyridinium tetracyanoborate ([3-mebupy]B(CN)(4)) and 1-butyl-1-methylpyrrolidinium tetracyanoborate ([1-mebupy]B(CN)(4)). viz, liquid density, viscosity, surface tension, thermal stability, and heat capacity over the temperature range from 283.2 K to 475.2 K and at 0.1 MPa. The density and the surface tension were well correlated with linear equations and the viscosity with a Vogel-Fulcher-Tamman equation. The IL [3-mebupy]B(CN)(4) is stable up to a temperature of 480 K and the IL [1-mebupyr]B(CN)(4) up to a temperature of 548 K. Ternary data for the systems ((benzene + n-hexane), or (toluene + n-heptane), or (p-xylene + n-octane + [3-mebupy]B(CN)(4))} were determined at T = 303.2 K and 328.2 K and p = 0.1 MPa. All experimental data were well correlated with the NRTL model. The values of the experimental and calculated aromatic/aliphatic selectivity are in good agreement with each other. The LLE data of [1-mebupyr]B(CN)(4) were only measured in a 10 vol% aromatic feed for the three systems. (C) 2011 Elsevier Ltd. All rights reserved.