Clément Georges Lemoine (16 January 1841 in Tonnerre – 13 November 1922 in Paris) was a French chemist and hydrologist.
For many years he was associated with the École Polytechnique in Paris, where he ultimately served as a professor of chemistry from 1898 to 1911.
[1][2] In 1866 he began work as an engineer in charge of hydrometric services in the Seine Basin.
He continued research on the allotropic transformation of phosphorus, and was also the author of works on chemical equilibria.
[2] In 1899 he became a member of the Académie des sciences (chemistry section), of which in 1921, he was named its president.