A facile topochemical route has been developed to synthesize porous LiMn2O4 spheres by using molten LiOH and porous Mn2O3 spheres as a template. The presence of pores with the average size of about 45 nm throughout the whole LiMn2O4 microspheres was confirmed by transmission electron microscope (TEM) and N2 adsorption–desorption measurements. When applied as cathode materials for rechargeable lithium-ion batteries, the porous sphere LiMn2O4 revealed stable high-rate capability. The discharge capacity is 83 mAh g−1 at 20 C rate, and it shows a good capacity retention after cycling at constantly changing discharge rate. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn2O4 spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries.