Glucosamine phosphate having a purity of at least about 99 wt. %, and a maximum halide content of about 0.01 wt. %. Preferably, the glucosamine phosphate is stabilized by coating it with at least one pharmaceutically acceptable polymer comprising a water-soluble, water-immiscible and/or water-swellable homopolymer and/or copolymer. Suitable polymers include carboxypolymethylene hompolymers and copolymers; polyethylene glycol homopolymers and copolymers; polypropylene glycol homopolymers and copolymers; ethylcellulose; povidone homopolymers and copolymers; polyacrylic acid homopolymers and copolymers; polyacrylamide homopolymers and copolymers; polysaccharides; and mixtures of two or more of the foregoing polymers. The resultant coated glucosamine phosphate composition will be stable at ambient temperatures and upon exposure to the atmosphere.