Experimental mole fraction solubility of lamotrigine (LTG) in temary aqueous mixtures of two ionic liquids (ILs), 1-hexyl and 1-octyl-3-methylimidazolium bromide, [HMIm][Br] and [OMIm][Br] were reported at several temperatures T - (293.15 to 313.15) K. The van't Hoff and (Jouyban-Acree-van't Hoff, E-Jouyban-Acree-van't Hoff, e-NRTL, UNIQUAC and Wilson) models were used to correlate the solubility data. The comparison of the models with temperature and solvent composition dependencies shows that the Wilson model has the minimum ARD which are relatively close to those obtained from Jouyban-Acree-van't Hoff and E-Jouyban-Acree-van't Hoff models and maximum ARD belonged to the UNIQUAC model. The order of ARDs for these models is: Wilson < Jouyban-Acree-van't Hoff, E-Jouyban-Acree-van't Hoff < e-NRTL < UNIQUAC. Moreover, the apparent thermodynamic functions, Gibbs free energy, enthalpy and entropy of dissolution and mixing were calculated based on the van't Hoff and Gibbs free energy equations. The strong LTG-ILs interactions and enthalpic contribution of the dissolution process resulted from the calculated thermodynamic functions. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.