Hugh (1788-1827), a distinguished African traveller, was born at Annan, Dumfriesshire, where his father was a surgeon. Having acquired some knowledge of practical mathematics, including navigation and trigonometry, he was apprenticed at the age of seventeen on board a large vessel which traded between Liverpool and North America. After having made several voyages across the Atlantic, he was impressed for the navy, and sent on board the Clorinde, where his intelligence and activity soon raised him to the rank of midshipman. In 1813 he was sent with a number of others to Plymouth dockyard to be drilled in the improved cutlass exercise, and afterwards drafted on board the Asia, the flag-ship of Vice-admiral Sir Alexander Cochrane, to the crew of which, then on a voyage to Bermuda, he acted as drill sergeant. He was next ordered to the command of a flotilla on the Canadian lakes, promoted to the rank of lieutenant, and soon afterwards to the command of a schooner. In the year 1817, when the flotilla on the lakes was dismantled, he returned to his native country on half pay.

In 1820 Clapperton removed to Edinburgh, where he contracted an intimacy with Dr Oudney, who first directed his attention to the cause in which both were destined to perish. After the return of Captain Lyon, the British government determined on equipping a second expedition for the purpose of exploring northern Africa. Dr Oudney was accordingly appointed to proceed to Bornu as consul, and Captain Clapperton and Colonel Denham were added to the party. After having arrived at Tripoli, they set out early in 1822, in a line nearly south to Mourzook, where they arrived on the 8th of April. Circumstances, however, having prevented them from proceeding farther, Clapperton and Oudney made an excursion to the westward into the country of the Tuaricks, which they penetrated as far as Ghrat, E. Long. 11.

On the 29th Nov. Clapperton, with his fellow travellers, set out for the kingdom of Bornu, and on the 17th Feb. 1823 reached Kouka the capital, where they were well received by the sultan; and remaining here till the 14th Dec., they again set out for the purpose of exploring the course of the Niger. They arrived in safety at Murmur, where Oudney breathed his last in the arms of his companion. Clapperton, however, penetrated alone as far as Sackattoo, N. Lat. 13. and E. long. 6½, which was the extreme point of the expedition in that direction. Circumstances prevented him from proceeding to the Niger, which lay only five days' journey to the westward. On returning to Kouka he was rejoined by Denham, who scarcely knew his emaciated associate. The two travellers then set out for Tripoli, and thence proceeded to England, where they arrived on June 1, 1825. The results of this expedition were embodied in a work containing the travels of Denham, Clapperton, and Oudney.

Immediately after his return Clapperton accepted the conduct of another expedition to Africa, and set out in August 1825, in company with Captain Pearce, Mr Dickson, Dr Morrison, and a youth named Richard Lander as his servant. On this occasion he landed at Badagry, in the Bight of Benin, and immediately commenced his journey into the interior, along with Lander and two of the others. Both of them, however, soon fell victims to the hardships of the journey. In January 1826, Clapperton reached Katunga, the capital of Youriba, and soon afterwards crossed the Niger at Boussa, the place where Park met his untimely fate. In July he arrived at Kano, a city which he had previously visited. Here he left his servant with the baggage, and proceeded alone to Sackattoo, intending to obtain permission from Bello, the sultan of Sackattoo, to visit Timbuctoo, and revisit Bornu. But his plans were frustrated in consequence of a war which Bello was then waging with the sheik of Bornu, to whom Clapperton bore considerable presents from the king of England. While he was detained by bad health at Sackattoo, the sultan deceiving Lander persuaded him to join his master with the baggage; and on his arrival the intended presents were immediately seized, and the travellers prohibited from proceeding farther.

For some months Clapperton enjoyed tolerable health, but on 13th March 1827, having been suddenly attacked with dysentery, he lingered on till the 13th April, when he expired in the arms of his faithful servant.

Although Clapperton failed in the main object of his ambition, which was afterwards accomplished by Lander, he contributed materially to the advancement of our geographical knowledge of northern Africa. (See Africa.) On the return of Lander to England he published a work entitled "Records of Captain Clapperton's last Expedition to Africa," which appeared in 1830, in 2 vols. 12mo.