Two tetradentate N2O2 type Schiff bases, 8-amino-[1-(2-hydroxyphenyl)imino]naphthalene (Salnaph) and N,N-bis(salicylidene)-1,2-cyclohexadiamine (Salcn), have been synthesized and their densities in ionic liquid, 1-penthyl-3-methylimidazolium bromide ([PnMIm]Br)+N,N-dimethyl formamide (DMF) solutions measured at 298.15 K. These data have been used to calculate apparent molar volumes, V-phi, standard partial molar volumes, V-phi(0), transfer partial molar volumes, Delta V-tr(phi)0, pair volumetric interaction parameters, V-sl, triplet volumetric interaction parameters, V-sll, (calculated using McMillan Mayer theory) interaction volumes, V-int, and cavity volumes, (V) over bar (cav), (calculated by use of scaled particle theory) for the solutions studied. All of 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 solutions in terms of scaled particle theory (SPT). (C) 2013 Elsevier B.V. All rights reserved.