Spray-dried particles were prepared with alpha-glucosyl hesperidin (Hsp-G), a hesperidin derivative with enhanced water solubility, to improve the solubility profile of naringenin (NRG). Naringenin was used as a model hydrophobic polyphenol. The spray-dried sample of NRG in the presence of Hsp-G formed 3-4 mu m spherical particles. Those particles showed a halo pattern in powder X-ray diffractometry, indicating the amorphous state of NRG in the solid dispersion with Hsp-G. Interestingly, the obtained powders dissolved immediately into the aqueous media and demonstrated dramatically high apparent solubility, over 60-fold greater than NRG crystals, when the loading ratio of NRG/Hsp-G was 1/20. The apparent solubility of NRG increased in proportion to the amount of Hsp-G loaded (R-2 > 0.99). These results suggested that a specific molecular interaction, a micelle-like structure in which NRG was incorporated with Hsp-G molecules, was formed in spray-dried particles, resulting in the anomalous enhancement in the solubility of NRG. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.