Who discovered hydrogen?
Henry Cavendish in 1766 identified Hydrogen as a discrete substance while studying a chemical reaction between metal and acid, in 1781 he found that the gas evolved in the reaction between metal and acid produces water when burned. He is known as the discoverer of Hydrogen.
Also, Antoine Lavoisier in 1783 have the name of Hydrogen to this gas after he confirmed Cavendish's finding that Hydrogen produces water when burned.