Arthur Smithells, CMG FRS (24 May 1860 – 24 February 1939) was a British chemist.

He was educated at the University of Glasgow and then spent time under Roscoe and Schorlemmer at Owens College, Manchester.

Smithells went on to be pro-vice-chancellor at Leeds, a post he held until he retired from his chair as emeritus professor in 1923.

During his career Smithells was honorary educational adviser on home science and household economics to King's College London (appointed 1907), president of the Society of British Gas Industries (1911).

His research was predominantly focused on flames, the process of burning and flame spectroscopy[2][3][4] During the First World War, Smithells was an adviser to the Northern Command, becoming Lieutenant-Colonel-Chief Chemical Adviser (Anti-gas Training) (1916-1919), for which in 1918 he was appointed a Companion of the Order of St Michael and St George (CMG).