Selenous acid is a chemical compound with the formula H2SeO3. It is a colorless, odorless liquid that is soluble in water and has acidic properties. Selenous acid is often used in laboratories and industrial applications, particularly in the synthesis of other selenium compounds. This acid is a weak acid and can act as a reducing agent. It is important in various chemical reactions and can be produced by dissolving selenium dioxide in water. Due to its potential toxicity, proper safety measures should be taken when handling selenous acid.