Born at Glasgow on 25 January 1814, the son of a minister of the Free Church of Scotland, he was attracted to Methodism as a teenager, became an 'exhorter' at 15, and a Local Preacher shortly afterwards. Accepted as a candidate for the ministry he completed his education at Glasgow University, graduating B.A. in 1840. In the same year he entered the ministry, and offered for foreign missionary service. Distinguished as a scholar in both language and mathematics, he also had a gift for teaching and that brought him into notice as an educationist. Because of his special skills he was released by the Missionary Committee in 1841 to serve on the staff of the Government College at Colombo, Sri Lanka.
He was put in charge of the Institution, but chose not to enter into permanent Government employment when the offer was made. He described his work in that setting as: 'a student in the morning, a schoolmaster in the forenoon, a pastor in the afternoon moving from hut to hut, and a preacher in the evening.' For his work in this field he was awarded an LL.D. in 1848 by Glasgow University. He returned from Ceylon in 1856 and from 1857 to1860 was stationed in France.
On his return Kessen remained 'under the direction' of the Missionary Committee, particularly for the tuition of young missionaries designated for the East. This was before the establishment of the [[Entry:2310 Richmond Missionary College]] in 1868. It would seem, however, that other men, appointed to minister in New Zealand and the West Indies, for example, were sent to him for personal tuition.
After he had turned 60 he was persuaded by the Missionary Committee to undertake the headmastership of the proposed Jamaica Institution, with a view to training young indigenous ministers. He was in poor health, however, and a return to the tropics was risky.He nevertheless went to Jamaica at the beginning of 1876 to what was the first High School there, if not in the West Indies.He had an assistant minister with him, but when they arrived they found the new High School was not ready. The additional strain of working in an unfinished setting undermined his already frail health and he stayed in Jamaica for only nine months.
On reurning to England in 1879, he lived in retirement in Dover. But while on a recuperative visit to the Channel Islands, he died of dysentry in Jersey on July 19th 1879. In 1873 he had married Matilda Burt Priest (1838-1920), later to become the wife of the notable former Fijian missionary, James Calvert, in 1889.