For zero tail pipe emission transportation, fuel cell technology is the best available option for replacing commercial IC engines. Worldwide lot of research work is going on in development of fuel cell vehicles.This work deals with the virtual development of system architecture for hybrid electric - fuel cell light commercial vehicle. The goal of this research work is to virtually design, model and convert an existing LCV model in to a hybrid electric fuel cell vehicle for the same performance and better efficiencies with zero tail pipe emissions. A unique fuel cell management system is developed and used for obtaining better efficiencies.A mathematical model of the vehicle is developed using GT-Drive which tracks the energy flow and fuel usage within the vehicle drivetrain. The vehicle is tested on chassis dynamometer to provide data for validation of the mathematical model. Model results and vehicle data show good correlation when validated. The combustion engine of the vehicle mathematical model is replaced by the Fuel Cell-Battery system which drives the selected electric motor for the same or better performance.A proper architecture design is laid out and is simulated using GT- Drive for new European driving cycle. The performance and efficiencies of the FCV model is compared with the existing Vehicle data.