Two different types of single-crystalline lithium lanthanum titanate (LLT) I LiCoO2 assemblies were prepared by depositing HT-LiCoO2 on the LLT surfaces of(1 10)p and (112)p to investigate the effects of the orientation dependence of microstructures on the electrochemical properties of the assemblies. Cyclic voltammetry shows that the (110)p assembly exhibits very small peak separation between anodic and cathodic reactions, while the peak separation is considerably large in the case of the (112)p assembly. In the HT-LiCoO2 thin film cathode formed epitaxially on LLT, four differently-oriented domains can be formed under the orientation relationships of (11 1)p//(000l) LiCoO2, and (110)p//(1l2O)LiCoO2 between LLT (macroscopically cubic) and HT-LiCoO2 (rhombohedral). The HT-LiCoO2 domains with their layered structure aligned perpendicular to the interface are dominantly formed for the (110)p assembly, whereas those with the layered structure inclined about 20° against the interface are dominantly grown for the (1l2) assembly. Such a selective growth behavior of the HT-LiCoO2 on the LLT surface is considered to play an important role for the observed orientation dependence of the electrochemical properties of the LLT/LiCoO2 assemblies.