LITHIUM-ION BATTERIES ARE USED WIDELY AS MOBILE DEVICES LIKE CELLPHONE AND NOTEBOOK. RECENTLY, RESEARCHERS ARE ACTIVELY DEVOTED INTO THE LITHIUM-ION BATTERY RESEARCH FOR HIGH ENERGY CONVERSION SYSTEM, SUCH AS ELECTRIC VEHICLE. LICOPO4 WITH OLIVINE STRUCTURE WHICH IS THE PROMISING CANDIDATE FOR HIGH VOLTAGE CATHODE MATERIAL WAS SYNTHESIZED BY HYDROTHERMAL METHOD. IN ORDER TO SYNTHESIZE HIGH PURITY AND WELL-DEFINED LICOPO4, SEVERAL PRECURSORS FOR LI, CO, AND P SOURCES AND HYDROTHERMAL REACTION PARAMETERS INCLUDING TEMPERATURE AND [H2O]/[CO] VALUE ARE OPTIMIZED. BY ANALYZING THE STRUCTURE, CO VALENCE, MORPHOLOGY, AND CHEMICAL RATIO VIA XRD, XPS, RAMAN, SEM, AND ICP LICOPO4 SYNTHESIZED FROM MANGANESE ACETATE TETRAHYDRATE HAVE SINGLE PHASE OF LICOPO4 WITHOUT IMPURITY AND SHOWED CHARGE AND DISCHARGE REACTION CAUSED BY CO REDOX. SPECIFIC CAPACITY OF SYNTHESIZED LICOPO4 GREW UP DURING CYCLING. IN OTHER PHRASES, WHEN HYDROTHERMAL TEMPERATURE WAS SET AT 1500C AND [H2O]/[CO] VALUE WAS SET AT 15, DISCHARGE CAPACITY AS HIGH AS 70 MAH/G WAS OBTAINED AT 1.20 C RATE.