Novel semi-conducting liquid crystalline materials comprise the radical salt of a mesogen. Preferred mesogens are those which form a discotic liquid crystalline phase. The materials may be produced by heating the mesogen in the isotropic phase with a dopant which is an oxidising agent or a reducing agent. The preferred materials exhibit anisotropic conduction properties in the liquid crystalline and the solid phases. The materials are useful in a variety of electronic and opto-electronic devices.