A high-resolution powder neutron diffraction study of the potassium bronzes KV5O13 and K2V8O21 is proposed. The structure of KV5O13 is unknown, while K2V8O21 is believed to exhibit polymorphism. These materials are currently under investigation as positive electrode materials in lithium batteries and show good electrochemical behaviour and stability. Hydrothermal treatment enhances the electrochemical performance and the structural effects of this treatment will be investigated. Electrochemical intercalation of lithium reveals two distinct lithiated phases. The structures of these phases will also be investigated.