Potassium ascorbate is a compound with formula KC₆H₇O₆. It is the potassium salt of ascorbic acid (vitamin C) and a mineral ascorbate. As a food additive, it has E number E303, INS number 303. Although it is not a permitted food additive in the UK, the USA and the EU, it is approved for use in Australia and New Zealand. According to some studies, it has shown a strong antioxidant activity and antitumoral properties.