Richard Thornton was born on the 5 April 1838 in Yorkshire, England. He attended grammar school in Bradford before entering the Royal School of Mines, London, in October 1855. After 2 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 March 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. 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 the 21 April 1863, Thornton died on board the "Pioneer" in the upper reaches of the Shire River. He was 25 years old.