A new layered oxyselenide, Ba2CuO2Cu2Se2, was synthesized under high-pressure and high-temperature conditions and was characterized via structural, magnetic, and transport measurements. It crystallizes into space group I4/mmm and consists of a square lattice of [CuO2] planes and antifluorite-type [Cu2Se2] layers, which are alternately stacked along the c axis. The lattice parameters are obtained as a = b = 4.0885 angstrom and c = 19.6887 angstrom. The Cu-O bond length is given by half of the lattice constant a, i.e., 2.0443 angstrom. Ba2CuO2Cu2Se2 is a semiconductor with a resistivity of similar to 18 m Omega.cm at room temperature. No magnetic transition was found in the measured temperature range, and the Curie Weiss temperature was obtained as -0.2 K, suggesting a very weak exchange interaction. The DFT+U-eff calculation demonstrates that the band gap is about 0.2 eV for the supposed antiferromagnetic order, and the density of state near the top of the valence band is mainly contributed from the Se 4p electrons.