A new BEDT-TTF BEDT-TTFsBis ethylenedithio.tetrathiafulvalene.-based cation radical salt BEDT-TTF.2HgCl3PTCE TCEs 1,1,2-trichloroethane.was synthesized by using oxidative electro-crystallization at a constant current. Its structure was determined by four-circle X-ray diffraction method. The crystal belongs to monoclinic system, C2 space group with the unit cell parameters of as39.236 (5). A°, bs6.676 (1) A°, cs14.881 (3). A°, bs95.58 2.0, Vs3879.4 12. A°(3), Zs4. The structure shows that the BEDT-TTF radicals are stacked to form columns along the c-axis and arranged side-by-side to form one-dimensional uniform chains along the b-axis. The one-dimensional polymer HgCl3.nny, together with neutral TCE molecules, is also along the b-axis. Cationic BEDT-TTF sheets and anionic HgCly3 sheets are sandwiched along the a-axis. The room temperature resistivity of the single crystal was measured to be 3.33 VPm on the bc-plane. Its resistivity–temperature curve demonstrates a semiconductor behavior with an activation energy of 0.308 eV.