The formula of Calcium hypochloride is Ca(OCl)OCl. This is marketed as bleaching powder for water treament and as bleaching agent. Bleaching powder is a mixture of calcium hypochlorite and the basic chloride, CaCl2.H2O with some slaked lime. This compound is relatively stable and has greater available chlorine than sodium hypochlorite. It is a white solid. It strongly smells of chlorine owing to its slow decomposition in moist air. It is highly soluble in hard water, that has high mineral content, in contrast to soft water. It is more preferably used in soft to medium-hard water. It has two forms: dry and hydrated. Bleaching powder is used in disinfecting of drinking and swimming pool water. It is also used in sugar industry for bleaching sugar cane juice before its crystallization. Bleaching powder is known as an available chlorine substance.

More Info: en.wikipedia.org