oxidation-reduction

A chemical reaction that takes place between an oxidizing substance and a reducing substance. The oxidizing substance loses electrons in the reaction, and the reducing substance gains electrons. For example, rust forms when there is an oxidation-reduction reaction between oxygen contained in water or moist air (an oxidizing substance) and iron (a reducing substance). Oxidation-reduction reactions also occur when glucose (a type of sugar) and fat are broken down in the body to make energy. Also called redox.