Richard Thornton was born on 5 Apr 1838 at Cottingley Hall in the parish of Bingley in the West Riding of Yorkshire, England. He attended grammar school in Bradford before entering the Royal School of Mines, London, in Oct 1855. After two years, he passed his examination with great distinction and won a government prize and the De la Beche Medal for excellence in geological studies.

Sir Roderick Murchison was director of the Royal School of Mines; he was also a friend and patron of David Livingstone, to whom he recommended Thornton as geologist to the Zambezi Expedition. The appointment was confirmed early in 1858, and in Mar, Thornton joined the Colonial Office steamer 'Pearl', which was to take the Expedition from Liverpool to the Zambezi.

About 14 months after the Expedition reached the delta of the Zambezi, Livingstone discharged Thornton, accusing him of being idle and disobeying orders. Thornton was then 21 years old. These charges were brought by David Livingstone's brother Charles, also a member of the Expedition, and were accepted by Dr Livingstone without verification. Thornton, however, was determined to continue his geological explorations in Africa. He proved to have a knack for making friends and received much help, particularly from the Portuguese; one pioneering journey he made, soon after his dismissal by Livingstone, was with Portuguese traders up the Zambezi to Zumbo. In 1861, he accompanied the explorer Baron von der Decken (1833-1865) on his first attempt to climb Mount Kilimanjaro.

Returning to the Zambezi, Thornton was invited by Livingstone to rejoin the Expedition, and after some hesitation agreed to do so in an independent capacity. Nine months later, on 21 Apr 1863, Thornton died on board the 'Pioneer' in the upper reaches of the Shire River. He was 25 years old.