MoSe2 nanosheets embedded in a mesoporous carbon matrix is synthesized through a facile route, where molybdenum source is recrystallized forming nanocrystals and further react with selenium. To obtain fine nanocrystals, freeze-drying technique is used to creating a large subcooled temperature. With low MoSe2 content of ~ 54 wt%, the mesoporous MoSe2/C composite shows an initial capacity of 450 mA h g−1 and a reversible capacity of 276 mA h g−1 after 200 cycles.