The present invention relates to a novel crystalline hemihydrate polymorph of neridronic acid sodium salt, and a novel process for the preparation thereof comprising the steps of: 1) dissolving solid sodium neridronate in any crystalline form in water, at a temperature in the range from 70 to 90° C., to obtain an aqueous solution of sodium neridronate； 2) adding a solvent selected from the group consisting in ethanol, 1-propanol, and 2-propanol to the aqueous solution obtained from step (1), so that the final water:solvent volume ratio is in the range from 1:0.5 to 1:1, thus obtaining a suspension； 3) placing the suspension obtained from step (2) under mechanical stirring, at a temperature in the range from 60 to 95° C.； 4) recovering the crystalline hemihydrate form F of sodium neridronate formed in the previous step (3). The crystalline hemihydrate form F of sodium neridronate, particularly stable, may be employed in the preparation of solid oral pharmaceutical forms for use in the treatment of musculoskeletal and calcium metabolism disorders.
