Hydrothermally prepared MgSeO3. 2H(2)O consists of pairs of edge-sharing Mg
O6 (4O, 2H(2)O) octahedra [d(av) (Mg-O) = 2.095 (2) Angstrom]. These are li
nked by pyramidal SeO3 units [d(av) (Se-O) = 1.697 (2) Angstrom] and hydrog
en bonds forming a three-dimensional network.