This paper describes the development of a liquid cooling system of battery module with lithium-ion prismatic metal can battery cells that can be used in hybrid electric vehicles (HEV). Initially, a design concept of a liquid cooled battery module is selected based on the functional requirements associated with maximum battery cell temperature rise, temperature uniformity across the battery module, temperature uniformity within each individual lithium-ion prismatic battery cell, and total pressure loss of the liquid cooling system. A three-dimensional battery module thermal model and an analytical optimization approach are developed for selected design concept of the liquid cooled battery module. Finally, by performing analytical optimization study to examine the effects of geometries of the inlet duct, manifold, and the outlet duct on battery module thermal behavior and total pressure loss of cooling system, the optimal design concept of liquid-cooled battery module is identified to maximize its durability and driving range. (C) 2016 The Electrochemical Society. All rights reserved.