The chemistry and reactivity of ascorbic acid are reviewed with focus on its behaviour and potential behaviour in a wine environment. Use of ascorbic acid as a complementary antioxidant preservative to sulfur dioxide is covered, along with the metal-catalysed and radical-dependent manner by which it achieves this role. The relevant degradation products of ascorbic acid in aerobic and anaerobic conditions are presented, as well as the interaction of these degradation products with sulfur dioxide and other wine-relevant S compounds. Limitations in existing knowledge, particularly regarding the crossover between the antioxidant and pro-oxidant roles of ascorbic acid, are identified. (We recommend that you consult the full text of this article)