High Quality Content by WIKIPEDIA articles! Sodium chlorate is a chemical compound with the chemical formula (NaClO3). When pure, it is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 250 °C to release oxygen and leave sodium chloride. In September 2009, wholesale of sodium chlorate weedkiller was banned in all EU countries, but consumers were allowed to use and store the product until May 2010.