Steric parameters of N-phenylbenzo-, N-phenyl-4-methyl-3-nitrobenzo-, and N-phenyl-4-nitrobenzo-, hydroxamic acids were measured in N,N-dimethylformamide (DMF) as a function of their concentrations at T = (298.15, 303.15, 308.15, and 313.15) K. The apparent molar volume (V-phi), limiting apparent molar volume (V-phi(0)) at infinite dilution and the slope (S-V*) are calculated from the experimental values of density (rho) by applying the Masson's equation. The apparent molar expansibility at infinite dilution (phi(0)(E)), molar volume (V) and the excess molar volume (V-E) are also computed. The refractive indices (n) have been used to calculate the steric parameters, viz. molar refraction (R-M), polarizability (alpha) and excess molar refraction (R) of these molecules. The results show the strong solute-solvent interactions present in the system and thus, help to explore the molecular structure. (C) 2012 Elsevier Ltd. All rights reserved.