The four new quaternary copper(I)-selenides, Sr0.5CuZrSe3 (a=3.8386(7), b=14.197(2), c=10.1577(17) Å), Ba0.5CuZrSe3 (a=3.8386(7), b=14.196(2), c=10.1577(17) Å), SrCuYSe3 (a=10.620(2), b=4.1000(8), c=13.540(3) Å) and BaCuYSe3 (a=4.1800(7), b=13.940(2), c=10.6200(17) Å) were synthesized by high-temperature solid state reactions and their crystal structures were determined using single-crystal X-ray diffraction. A0.5CuZrSe3 (A= Sr, Ba) and BaCuYSe3 crystallize in the KCuZrS3 structure type (Cmcm), while SrCuYSe3 is isostructural to Eu2CuS3 (Pnma). All compounds form layered structures in which the charge of the [CuZrSe3]−∞2 and [CuYSe3]2−∞2 layers as well as the site occupancy of the A cations depend on the transition metal. Combining the alkaline earth metals Sr and Ba with tetravalent Zr leads to the formation of cation vacancies between the [CuZrSe3]−∞2 layers and structure type as well as symmetry are determined by the ratio between the cation and transition metal ionic radii r(A2+)/r(M 3+/4+). © 2016 Elsevier Inc.