As part of our research into novel cathodes for sodium ion batteries we request beamtime to study the structures of a series of bimetallic sulphates. Sodium transition metal sulphates of the formula Na2M(SO4)2 can be synthesised by the dehydration of the bimetallic hydrate Na2M(SO4)2.xH2O. There are several different polymorphs that can be formed depending on the synthesis parameters and dehydration temperatures. To date we have synthesised two polymorphs of Na2Fe(SO4)2 and Na2Mn(SO4)2, as well as Co and Ni analogues. X-ray diffraction data indicate a monoclinic cell in all cases, however the structures are difficult to solve using X-ray diffraction techniques. It is proposed to combine X-ray and neutron diffraction studies to elucidate this problem.