In hybrid electric vehicles (HEVs) and full electric vehicles (EVs), efficient electrical power management with proper supply of power at the required voltage levels is essential. A DC (Direct Current)-DC converter is one of the key electrical units in a HEV/EV. The DC-DC converter dealt in the present work is intended to create the DC voltages necessary to power the accessories. The electronic circuit in this DC-DC converter consists of high power devices like Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs), inductors, transformers, etc. mounted on a printed circuit board (PCB). The DC-DC converter interacts with a high voltage battery pack and supplies a low voltage power to the accessory battery. Due to this power handling operation, the devices in the convertor experience high temperatures. The temperature rise of the devices beyond the permissible limits could be detrimental to an efficient and safe operation of the converter.This paper deals with a robust and optimal thermal design of an air-cooled DC-DC Converter in order that the temperature (primary design parameter) of each of the devices is at a minimum and below the corresponding permissible limit of the device. Additionally, a design feasibility study is conducted for optimum material utilization and packaging space.The Robust Engineering (RE) experiments are conducted using Computer Aided Engineering (CAE)-virtual simulation based on a non-linear finite volume method. The paper also provides an understanding of the relative magnitude of the influence of various design features upon the temperature of each of the devices. The study helps to realize the benefits of using a RE design approach in conjunction with a reliable CAE analysis.