Dissolution thermodynamics of (2Z)-N-cyclohexyl-2-(3-hydroxybenzylidine) hydrazine carbothioamide (CHBH) in various polyethylene glycol-400 (PEG-400) + water mixtures from (298.15 to 338.15) K were studied and correlated. The experimental solubilities were correlated with the modified Apelblat and Yalkowsky models. The root mean square deviations (RMSD) were observed as (0.88-4.28)% for the modified Apelblat model and (2.10-8.25)% for Yalkowsky model. The mole fraction solubility (7.12 x 10(-2) at 298.15 K) and mass fraction solubility (5.32 x 10(-2) kg kg(-1) at 298.15 K) of CHBH were observed highest in pure PEG-400. However, the lowest mole fraction (3.83 x 10(-7) at 298.15 K) and mass fraction solubility (5.90 x 10(-6) kg kg(-1) at 298.15 K) of CHBH were observed in pure water. Thermodynamic studies showed endothermic and spontaneous dissolution of CHBH in all co-solvent mixtures. (C) 2014 Elsevier B.V. All rights reserved.