Synthetic routes for LiCoO2 mesocrystals with porous and single-crystalline structures through the topotactic transformation of precursor crystals are developed. Octahedral LiCoO2 frameworks of 4–6 μm in diameter, consisting of 600–800 nm subunits, are obtained from octahedral solid particles of Co2(OH)3Cl. Hollow LiCoO2 plates about 600 nm wide and 40 nm thick composed of 100–400 nm subunits are produced from hexagonal disks of β-Co(OH)2. The LiCoO2 mesocrystals exhibit enhanced charge–discharge cycle stability and rate performance as a cathode material for lithium-ion batteries. The high reactive surface area, owing to the porous framework, and high lithium-ion and electron conductivities, originating from the single-crystalline nature, effectively enhance their electrochemical properties.