Most of the organic conductors based on CH-TTP derivatives, where CH-TTP is 2-(4,5-cyclohexeno-1,3-dithiol-2-ylidene)-5-(1,3-dithiol-2-ylidene)- 1,3,4,6-tetrathiapentanlene, behave metallic down to low temperatures. An X-ray crystal structure analysis of CHEO-TTP(RcO(4))(0.38) revealed that the arrangement of the donors is close to that of the kappa-BEDT-TTF salts. The band structure calculated with the tight-binding approximation suggests that the ReO4- salt has a closed Fermi surface similar to those of the kappa-type superconductors.