The magnetic order in the tetragonal M 2CuO 2Cl 2, M=Ca,Sr and in Sr 2CuO 3+x compounds was studied by using Mossbauer spectroscopy of 0.5% 57Fe-doped samples. These compounds crystallize in a K 2NiF 4 - type tetragonal structure, isostructural to La 2-xSr xCuO 4 superconductors. In this structure, one crystallographic site exists for copper atoms, which form CuO 2 planes. Sr 2CuO 3 prepared under ambient pressure has an orthorhombic structure, while the tetragonal Sr 2CuO 3+x is obtained when prepared under high oxygen pressure. Both copperoxychlorides are antiferromagnetically ordered with T N≈260K, very similar to T N in La 2CuO 4 or Nd 2CuO 4. The strontium-cuprates are magnetically ordered at 4.2K with T N below 10K.