pro-Czech Austrian statesman and administrator who improved the educational establishments of the Austrian Empire, sought to resolve the antagonisms between Czechs and Germans in Bohemia, and favoured the conversion of the Habsburg monarchy into a federal state.

Leo was the younger brother of Friedrich, Count von Thun und Hohenstein. He was basically conservative but was much affected by the Romantic movement and sympathetic to the national aspirations of the Czechs, Poles, and Hungarians in the Habsburg empire. As Austrian minister for religious affairs and education (1849–60), he allowed instruction in some primary schools to be conducted in the regional languages and raised the quality of higher education by bringing in scholars from Germany. The 1855 concordat between Austria and the papacy, however, reestablished Roman Catholic control over education. Thun served as governor of Bohemia in 1848 and was again active in Bohemian politics after 1861. He favoured greater rights for Czechs and became a spokesman of the “feudal” party of Bohemian aristocrats, working toward the federalization of the Habsburg empire.