Nanosized LiyMnSiOx and LiMnPO4 have been synthesized by a hydrothermal route. Simply by changing parameters such as metal precursors and/or template, high surface area LiyMnSiOx with different morphology and sizes were prepared, in particular hollow spheres and plate-like nanoparticles, however with poorly developed crystallinity. In the case of LiMnPO4, highly crystalline nanocrystals were prepared.