Sonia Cotelle, née Slobodkine (19 June 1896 – 18 January 1945), was a Polish radiochemist.
Sonia Cotelle was born in Warsaw, capital of the Vistula Land, in the Russian Empire on 19 June 1896.
While still a student, she began working in 1919 as an assistant in the Institute of Radium (French: Institut du Radium) founded by the Nobel Laureates, Marie Curie and her husband Pierre, in the university's Faculty of Science (French: Faculté des sciences).
Cotelle was in charge of the measurement service between 1924 and 1926, after which she was appointed as a chemist in the Faculté des sciences.
With Curie, she redetermined the half-life of ionium using a method that minimized effects of error in atomic weights.