Densities of ternary mixtures of some Schiff bases N,N'-salicylidenephenylediamine (Salophen), N, N'-bis(salicylaldehyde)-1,3-diaminopropane (Salpr), N, N-bis(salicylidene)-1,2-cyclohexadiamine (Salcn) + ionic liquid, 1-penthyl-3-methylimidazolium bromide ([PnMIm]Br) + N,N-dimethylformamide have been measured at (308.15, 318.15 and 328.15) K. These data have been used to calculate apparent molar volume, V-phi, the standard partial molar volume, V-phi(0), standard partial molar volume of transfer, Delta V-tr(phi)0, standard partial molar isobaric expansion, Ep, (0)(phi) and isobaric thermal expansion coefficient (alpha) for the mixtures studied. All these parameters were used to interpret the effect of ionic liquid on the solute-solvent interactions and solvation behavior occurring between ionic liquid and Schiff bases in these ternary mixtures. (C) 2012 Elsevier Ltd. All rights reserved.