Masao Doi

(born 29 March 1948) is a Professor Emeritus at Nagoya University and The University of Tokyo. He is a Fellow of the Toyota Physical and Chemical Research Institute. In 1976, he introduced a second quantised formalism for studying reaction-diffusion systems. In 1978 and 1979 he wrote a series of papers with Sir Sam Edwards expanding on the concept of reptation introduced by Pierre-Gilles de Gennes in 1971.

In 2001 the American Physical Society awarded Doi the Polymer Physics Prize for "pioneering contributions to the theory of dynamics and rheology of entangled polymers and complex fluids."

He was also awarded the Bingham Medal in 2001 by the Society of Rheology.