Thomas Welton OBE FRSC CChem FCGI (born January 1964) is a professor of sustainable chemistry at Imperial College London.

Since 2013 he has been a member of the Council of the Royal Society of Chemistry[4] and additionally serves on the steering committee for the RSC's diversity programme.

[13] Welton works in the field of sustainable chemistry, and has spent most of his career studying the properties of ionic liquids, their interactions with solutes, and the resulting effects on chemical reactions.

[15] His research group also works on applications for these phenomena in developing environmentally safe organic synthesis methods and in the production of biofuels.

[27] Welton's work on ionic liquids led to the invention of a method to process wood by separating its chemical component lignin from hemicellulose and cellulose, which is potentially applicable to the efficient production of biofuels.

[28] Welton also comments in the media on matters related to the health of the environment, such as the 2012 shortage of helium gas commonly used in research laboratories.

[32] In 2014, together with Alison Rodger, Welton established the Irène Joliot-Curie conference that looked to develop the careers for women and underrepresented groups in science.

[6] Additionally, Welton is a L'Oréal-UNESCO For Women in Science male laureate of change, "The time for men to realise that gender parity benefits everyone is long overdue".