Abstract Densities of binary mixture of three ionic liquids, 1-butyl-3-methylimidazolium thiocyanate (C4C1imSCN), 1-allyl-3-methylimidazolium thiocyanate (C1 = C2)C1imSCN) and 3-(3-butyl-1H-imidazol-3-ium-1-yl)propanenitrile thiocyanate ((NC)2C2C4imSCN), with methanol were measured over a temperature range of 293.15 to 323.15 K and at atmospheric pressure. Excess molar volumes (VmE) were calculated from density values and correlated with Redlich-Kister polynomial equation. Partial molar volumes at infinite dilutions (Vm,i�) of the ILs and methanol were determined from the Redlich-Kister coefficients. For all the studied systems, the VmE is negative over the entire composition range. The VmE and Vm,i� are interpreted in terms of intermolecular interactions in the binary mixture. Density functional theory has been used to investigate the interactions between methanol and the studied ILs. © 2015 Elsevier B.V.