Conventionally, magnesium sea water activated batteries are employed as main power source to torpedoes and other under water vehicles. With the advent of lithium-ion battery technology, efforts are being concentrated to develop a suitable battery unit for these under water applications. In this regard, investigations have been carried out experimentally to study the charge and discharge characteristics of lithiumion polymer (Li-Po) batteries. A single cell module has been used to study the discharge voltage under constant currentmode using 1C, 2C, 3C and 4C discharge rates. Variation in temperature of anode and cathode were also measured. The rise in temperature of anode and cathode were correlated in terms of time and Crate by regression analysis. Charging characteristics of the single cell were also investigated at 1C rate. The discharge voltage characteristics of all individual cells of a 9-cell packwere also obtained at 1Crate and compared. It was found that all the cells in the 9-cell pack exhibited almost uniform discharge voltage.