In 1950, first experimental evidence for the existence of photophosphorylation in vivo was presented by Otto Kandler using intact Chlorella cells and interpreting his findings as light-dependent ATP formation. 
In 1954, Daniel I. Arnon et.al. discovered photophosphorylation in vitro in isolated chloroplasts with the help of P. 
His first review on the early research of photophosphorylation was published in 1956.