A new charge-transfer salt containing hexachlorodicuprate (II) binuclear polychloride complex counter anions, ET 2 Cu 2 Cl 6 (ET = BEDT-TF=bis(ethylenedithio)-tetrathiafulvalene), was prepared. The room-temperature d.c. conductivity and relative resistance temperature dependence of the salt from room temperature down to 77 K along the longest crystal growth direction are reported. The crystal structure is determined by the X-ray diffraction method at room temperature. It belongs to the triclinic p1 space group with crystallographic parameters of a = 11.379(4), b = 16.353(4), c = 9.054(4) , α = 90.33(3), β = 100.69(3), γ = 100.06(2)°, V = 1628(1) 3 , Z = 2, d c = 2.261 g cm - 3 λ (Mo Kα) = 0.710 69 , μ= 28.45 cm - 1 , F 0 0 0 = 1104.00 and final R = 0.043, R w , = 0.057 for 2331 observed reflections. The structure consists of isolated ET stacks and the binuclear polychloride complex dianion (Cu 2 Cl 6 ) 2 - sheets. In the donor stack, significantly short S S contacts are observed.