Halvdan Koht got his M.A. degree in History in 1896. He was then granted a scholarship from the University of Kristiania (Oslo). After continued historical research and travels abroad, he finished his Ph.D. in 1908. He worked as senior lecturer at universities both in Europe and the USA until he became Professor at the University of Oslo in 1910.
Koht was originally a Liberal, becoming more radical during the 1890s. From 1896 he regarded himself as a socialist and became affiliated with the Labour Party. However, he did not officially become a party member until 1911. He soon became engaged in the local government in Oslo and gradually became a prominent Labour politician. Koht was Minister of Foreign Affairs in 1935-1941. After the Second World War he was strongly criticized as being responsible for the pre-war government’s policy of neutrality.
Halvdan Koht was engaged in the peace movement in the mid-1890s. From 1905 he attended numerous international peace conferences and in 1913 became a member of l’Institut International de la Paix. Koht served as permanent adviser to the Nobel Committee in 1904-1913. He was a member of the Norwegian Nobel Committee in 1918-1936.