The layered oxide chalcogenides Ba3-xSrxFe2O5Cu2Ch2 (x ​= ​0, 1, 2; Ch ​= ​S, Se) and BaCa2Fe2O5Cu2S2 are reported here for the first time. They are isostructural with the previously reported Sr3Fe2O5Cu2Ch2, crystallising in the I4/mmm space group. This structure is related to the n ​= ​2 Ruddlesden-Popper type structure which is common for oxides and contains Sr3Fe2O5 perovskite-related slabs intergrown with Cu2Ch2 layers which resemble fragments of the antifluorite structure. In the oxide slabs, a double layer of FeO5 pyramids is formed by the sharing of apical oxide ions. Structural analysis shows a clear partial ordering of the alkaline earth cations of different sizes over the available 12 and 8-coordinate sites which correlates with the size variation of the alkaline earth cations. Long range magnetic ordering on a √2a ​× ​√2a ​× ​c expansion of the nuclear cell reveals nearest neighbour Fe3+ moments coupling antiferromagnetically via all the Fe–O–Fe linkages. In Ba3Fe2O5Cu2Se2, the moments are oriented in the ab-plane, whereas in Ba3-xSrxFe2O5Cu2Ch2 (x ​= ​2; Ch ​= ​S, Se), the Fe3+ moments are tilted towards the c-axis, reflecting that high spin d5 ions with no orbital angular momentum have only a weak preference for a particular spin direction. Cation site preferences determine alkaline earth ion ordering in layered oxide chalcogenides and long range ordered Fe3+ moments are controlled by the degree of covalency. Display omitted •Novel iron oxide chalcogenides with Ba2+/Sr2+/Ca2+ ordering synthesised.•Ordered moment correlates inversely with Fe ion bond valence sum.•Long range antiferromagnetic ordering persists well above room temperature.•Magnetic ordering model depends on whether there is a single alkaline earth ion present, or a mixture.