[Abstract]A novel mixed-valence Cu(I)-Cu(II) coordination polymer having an infinite one-dimensional(1D) structure, [Cu^I_2Cu^IIBr_2(iPr-pip-dtc)_2]_n (1) (iPr-pip-dtc- = 4-isopropylpiperidine dithiocarbamate), has been prepared and structurally characterized via X-ray diffraction. Magnetic studies indicate that this complex including copper(II) ions exhibits a weak ferromagnetic interaction (θ = 0.52 K) between the unpaired electrons of the copper(II) ions through the diamagnetic Cu(I)-Br chains. The carrier transport properties of 1 are investigated using an impedance spectroscopy technique. The impedance spectroscopy reveals that this complex exhibits intriguing semiconducting properties at a small activation energy (E_a = 0.278 eV ).