Currently, studies on organic two-dimensional (2D) materials with special optic-electronic properties are attracting great research interest. However, 2D organic systems possessing promising electrical transport properties are still rare. Here a highly crystalline thin film of a copper coordination polymer, Cu-BHT (BHT=benzenehexathiol), is prepared via a liquid–liquid interface reaction between BHT/dichloromethane and copper(II) nitrate/H₂O. The morphology and structure characterization reveal that this film is piled up by nanosheets of 2D lattice of [Cu₃(C₆S₆)]_n, which is further verified by quantum simulation. Four-probe measurements show that the room temperature conductivity of this material can reach up to 1,580 S cm⁻¹, which is the highest value ever reported for coordination polymers. Meanwhile, it displays ambipolar charge transport behaviour and extremely high electron and hole mobilities (99 cm²V⁻¹s⁻¹ for holes and 116 cm²V⁻¹s⁻¹ for electrons) under field-effect modulation.

A highly crystalline copper(II) benzenehexathiolate coordination polymer (Cu‐BHT) has been prepared. The two‐dimensional kagome structure has been confirmed by powder X‐ray diffraction, high‐resolution transmission electron microscopy, and high‐resolution scanning transmission electron microscopy. The as‐prepared sample exhibits bulk superconductivity at about 0.25 K, which is confirmed by the zero resistivity, AC magnetic susceptibility, and specific heat measurements. Another diamagnetic transition at about 3 K suggests that there is a second superconducting phase that may be associated with a single layer or few layers of Cu‐BHT. It is the first time that superconductivity has been observed in a coordination polymer.