Fuel cell (FC) systems are potentially promising candidates as alternative energy sources for use in vehicular applications. The natural advantages of hybrid power sources may be effectively utilized to improve the efficiency and dynamic response of a vehicular system. Fuel cell (FC) and ultra-capacitor (UC) based hybrid power systems appear to be very promising for satisfying high energy and high power requirements for vehicular applications. In this paper, a FC/UC hybrid vehicular power system using a wavelet based load sharing and fuzzy logic based control algorithm is proposed. While wavelet transforms are suitable for analyzing and evaluating the dynamic load demand profile of a hybrid electric vehicle (HEV), the use of fuzzy logic controller is appropriate for the hybrid system control. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB (R), Simulink (R) and SimPowerSystems (R) environments. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.