Densities, refractive indices and excess molar volumes for binary mixtures of protic ionic liquids with methanol at TÂ =Â 293.15 to 313.15Â K

► Densities and refractive indices for four binary mixtures of protic ionic liquids with methanol are made. ► Excess molar volumes and thermal expansion coefficients for the above said four binary mixtures were estimated using experimental density data and the details are discussed. ► Redlich Kister type of polynomial equations are used to correlate the excess molar volumes.