The present invention has objects to provide a novel crystalline 2-O-α-glucosyl-L-ascorbic acid and its production process and uses, and solves the above objects by providing hydrous crystalline 2-O-α-glucosyl-L-ascorbic acid, a particulate composition containing hydrous crystalline 2-O-α-glucosyl-L-ascorbic acid, and their production processes and uses.