Sodium perborate is a white, free-flowing crystalounds soluble in water. Sodium Perborate is a stable, solid source of active oxygen. Sodium perborate exists in the anhydrous , mono, tri and tetrahydrate forms (mono and tetrahydrate forms are important commercially).Compare the properties of the hydrates of sodium perborate. The tetrahydrate is prepared from disodium tetraborate pentahydrate, hydrogen peroxide and sodium hydroxide. However, it is not as soluble as the monohydrate nor is it as stable at higher temperatures. Sodium perborate monohydrate is easily prepared by heating the tetrahydrate.