Research on the production of lithium hydroxide (LiOH) has been actively conducted in response to the increasingdemand for high nickel-based positive electrode materials for lithium-ion batteries. Herein we studied the conversion of lithiumoxide (Li2O) through thermal decomposition of lithium carbonate for the production of lithium hydroxide from lithiumcarbonate (Li2CO3). The reaction mechanism of lithium carbonate with alumina, quartz and graphite crucible during heattreatment was confirmed. When graphite crucible was used, complete lithium oxide powder was obtained. Based on the TGanalysis results, reagent-grade lithium carbonate was heat-treated at 700°C, 900°C and 1100°C for various time and atmosphereconditions. XRD analysis showed the produced lithium oxide showed high crystallinity at 1100°C for 1 hour in a nitrogenatmosphere. In addition, several reagent-grade lithium oxides were reacted at 100°C to convert to lithium hydroxide. XRDanalysis confirmed that lithium hydroxide (LiOH) and lithium hydroxide monohydrate (LiOH·H2O) were produced.