This paper presents the experimental results and an analysis of thermocline TES using a molten salt. A single-medium thermocline with two types of storage tanks were tested under various mass flow rates. The discharge performance of each type of thermal storage tank was evaluated according to the useful energy considering the discharge temperature, and the performance was found to vary greatly depending on the configuration of the storage tank. It was also confirmed that the high mass flow rate enhanced the performance despite the increased unnecessary mixing effect. Although the temperature maldistribution was increased under the condition of a high mass flow rate, it is considered that the reduced discharging time positively affects the performance for the corresponding Froude numbers of 0.4–1.4. This study provides meaningful experimental results for molten-salt thermocline TES and design guidelines for a thermocline TES system.