Study of complex formation of cyclodextrins with 1,2,4-thiadiazole derivatives intended for Alzheimer's disease treatment was carried out using H-1 NMR, ITC and phase solubility methods. Structure of cyclodextrins and thiadiazoles affects the binding mode and thermodynamics of complexation. The larger cavity of alpha- and beta-cyclodextrins is more appropriate for deeper insertion of 1,2,4-thiadiazole derivatives which is accompanied by intensive dehydration and solvent reorganization. Benzene ring of the thiadiazoles is located inside macrocyclic cavity while piperidine ring is placed outside the cavity and can form H-bonds with cyclodextrin exterior. Complexation with cyclodextrins induces the enhancement of aqueous solubility of 1,2,4-thiadiazole derivatives. (C) 2017 Elsevier B.V. All rights reserved.