We developed a formulation for increasing the water solubility of curcumin (CUR). The new formulation also protected CUR from hydrolytic degradation. A ternary system of CUR/alpha-glucosyl hesperidin (hesperidin-G)/polyvinylpyrrolidone (PVP) K-30 was prepared by the solvent evaporation method. Although the binary sample of CUR/hesperidin-G showed increased solubility, the effect disappeared within a few hours of storage in aqueous media. In contrast, the ternary system of CUR/hesperidin-G/PVP K-30 (1: 10: 5, weight ratio) exhibited a long-lasting solubility increase. This supersaturated CUR solution remained stable even after 24 h, as shown by the 2600-fold increase in solubility compared with untreated CUR. The stability of CUR to hydrolytic degradation under alkaline conditions was improved dramatically by adding hesperidin-G and PVP K-30, whereas untreated CUR completely decomposed after a few minutes. The solubilizing effect may arise from the formation of an amorphous solid dispersion, including CUR, and from complex formation between CUR, hesperidin-G, and PVP K-30 in aqueous media. The complex may also protect CUR from hydrolytic degradation. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.