The solubility of complex triterpenes Lup-20(29)-ene-3 beta,28-diol (betulin) and (8R,9S,13S,14S)-3-hydro xy-13-methyl-6,7,8,9,11,12,13,14,15,16-decahydrocyclopenta[a]phenanthren-17-one (estrone) in numerous common solvents were determined by combined thermal gravimetry and digital thermal analysis (TGA/DTA). The measurements were conducted at atmospheric pressure and within the temperature range of T = (293.2 to 328.2) K. Melting point and enthalpy of fusion data of the solutes considered were also determined by DTA/TGA. The measured values were modelled using the Non-Random Two Liquid (NRTL) and Tsuboka-Katayma modified Wilson activity coefficient models which incorporated polynomial temperature dependence. The models provided a very good correlation of the experimental values in most cases. (C) 2016 Elsevier Ltd. All rights reserved.