  We present the synthesis and structural characterisation of a transition
metal oxide hydride, LaSrCoO_3H_{0.7}, which adopts an unprecedented structure
in which oxide chains are bridged by hydride anions to form a two- dimensional
extended network. The metal centers are strongly coupled by their bonding with
both oxide and hydride ligands to produce magnetic ordering up to at least 350
K. The synthetic route is sufficiently general to allow the prediction of a new
class of transition metal-containing electronic and magnetic materials.
