He enters Jesus College, Cambridge just after the commencement of war with Germany in 1939. The result of the scholarship examination to enter Jesus College Cambridge is so dismally bad that he is only admitted to the University at all on the strength of a personal letter written by the Headmaster of his former College.

Peter Dennis Mitchell is born in Mitcham, in the County of Surrey, England.

Peter Mitchell is educated at Queens College, Taunton.

In 1965, Mitchell starts a programme of research on chemiosmotic reactions. At that time, the enzyme ATP was known to be the “energy currency” of life, but the mechanism by which it is created was unknown. Mitchell realises that the movement of ions across the cell membrane's potential difference can provide the energy needed to produce ATP. This chemiosmotic hypothesis turns out to be the basis for understanding the actual process of ATP synthesis.

He holds the post of Demonstrator at the Department of Biochemistry from 1950 to 1955. 

From 1963 to 1965, he withdraws from scientific research and acts as architect and master of works, directly supervising the restoration of an attractive Regency-fronted Mansion, known as Glynn House, near Bodmin, Cornwall, adapting and furnishing a major part of it for use as a research laboratory.

In 1955 he is invited to set up and direct a biochemical research unit in the Department of Zoology, Edinburgh University. He is appointed to a Senior Lectureship in 1961, to a Readership in 1962, and remains until illness leads to his resignation in 1963.

He accepts a research post in the Department of Biochemistry, Cambridge, in 1942 at the invitation of J.F. Danielli. He receives the degree of Ph.D. in early 1951 for work on the mode of action of penicillin.

Peter Mitchell is awarded the 1978 Nobel Prize in Biochemistry “for his contribution to the understanding of biological energy transfer through the formulation of the chemiosmotic theory".

Peter Mitchell dies in Bodmin (UK).