HEDP•Kx is the potassium salt of HEDP, HEDP•Kx has better dissolution ability than that of sodium salt under neutral condition. HEDP•Kx is a good scale inhibitor for calcium carbonate, it can be used in metal corrosion inhibitor, antifouling agent of swimming pool, metal cleaning, volume cleaning, iron dust controlling, metal pretreatment, low pressure boiler water treatment and circulating water treatment, etc.