Hill’s reaction is a process in photosynthesis where light energy is used to split water molecules into oxygen and hydrogen¹. The process is named after English scientist Daniel Hill, who first described it in 1887¹. In vivo, the final electron acceptor in the light reactions is NADP+¹². The Hill reaction can be measured in isolated chloroplasts¹².

The Hill reaction proved that the source of oxygen in photosynthesis is water, not carbon dioxide as previously believed². It also showed that the process of oxygen production is separate from the process of carbon fixation². Hill used artificial electron acceptors, such as DCPIP, a dye that changes color when reduced, to demonstrate the light-driven transfer of electrons from water to these acceptors². These acceptors are also known as Hill reagents².

(1) The Hill Reaction: A Key Step In Photosynthesis. https://www.artofbonsai.org/the-hill-reaction-a-key-step-in-photosynthesis/.
(2) Hill reaction – Wikipedia. https://en.wikipedia.org/wiki/Hill_reaction.
(3) Hill reaction | botany | Britannica. https://www.britannica.com/science/Hill-reaction.
(4) What is Hill Reaction? – QS Study. https://qsstudy.com/what-is-hill-reaction/.