Who discovered that oxygen is produced by green plants ?

It was not until the end of the 18th century that Joseph Priestley discovered by accident the ability of plants to "restore" air that had been depleted by the burning of a candle. read more

Results showed that the oxygen released from the first group of plants was radioactive, confirming that water is the source of the oxygen produced by photosynthesis. While seemingly simple, later studies went on to demonstrate that photosynthesis is a combination of two separate processes, each involving multiple steps. read more

This discovery predicted that water is the hydrogen donor in green plant photosynthesis and is oxidized to O2. This prediction was experimentally demonstrated by Robert Hill, a British plant biochemist who proved that oxygen is evolved during the light requiring steps of photosynthesis. read more