Sir Eric Keightley Rideal, MBE, FRS (11 April 1890 – 25 September 1974) was a British physical chemist. He worked on a wide range of subjects, including electrochemistry, chemical kinetics, catalysis, electrophoresis, colloids and surface chemistry. He is best known for the Eley–Rideal mechanism, which he proposed in 1938 with Daniel D. Eley. He is also known for the textbook that he authored, An Introduction to Surface Chemistry (1926), and was awarded honours for the research he carried out during both World Wars and for his services to chemistry.