In this work, the intermolecular interactions and structural features of binary 1-butyl-3-methylimidazolium bromide ([BMIM]Br) (1) + gamma-valerolactone (GVL) (2) and ternary solutions of [BMIM]Br) (1) + GVL (2) + methyl cellosolve (2-ME) or ethyl cellosolve (2-EE) or propyl cellosolve (2-PE) or butyl cellosolve (2-BE) (3) were investigated on the basis of respective density, \(\rho\) and \(\rho_{123}\) covering the whole composition range at temperatures from 298.15 to 313.15 K at interval of 5 K at atmospheric pressure of 0.1 MPa. From the density data, excess molar volume of binary, \(V_{\text m}^{\text E} ,\) and ternary, \(V_{\text m (123)}^{\text E},\) solutions was derived. The predicted data of binary system was fitted to Redlich–Kister polynomial smooth equation to obtain the binary adjustable parameters and standard deviations between experimental and best-fit values. Further, Singh and Nagata–Tamura equation was used to estimate ternary coefficients. In addition to this, the structural profile of working solutions was discussed by analysing \(V_{\text m}^{\text E}\) data in terms of Graph and Prigogine–Flory–Patterson (PFP) theories. Graph theory was also used to derive an expression for \(V_{\text m (123)}^{\text E}\) of ternary mixtures and results showed the good agreement between estimated and experimental \(V_{\text m (123)}^{\text E}\) data. Furthermore, Fourier transform infrared spectroscopy (FT-IR) was used to investigate the molecular association in binary and ternary systems.
