Preparation of radical cation salts based on 1,3-dithiane derivatives (1,2 and 5-8) was investigated. Although attempts to prepare stable radical cation salts derived from 1 and 2 were unsuccessful, various radical cation salts composed of TTF (tetrathiafulvalene) derivatives fused with a 2-(1,3-dithiol-2-ylidene)-1,3-dithiane (DTDT) unit (5-8) were formed with ease by electrochemical oxidation. Several radical cation salts of 6-8 exhibited metallic conducting behaviors on a single crystal or compressed pellets.