Mesoporous beta-MnO2 (rutile structure) with a highly ordered pore structure (see figure) and highly crystalline walls is capable of reversibly accommodating lithium, up to a composition of Li0.92MnO2 (equivalent to a charge storage of 284 mA h g(-1)). Remarkably, the crystal structure and the ordered mesostructure are preserved after many cycles (Li intercalation/deintercalation).