The hydrogen economy is seeking its killer application which can break down the chicken and egg problem i e no hydrogen powered car can be sold if it cannot be refueled and nobody will invest to a hydrogen refueling station if no one has a hydrogen powered vehicle The applications like material handling backup power and small stationary combined heat and power (CHP) engines are the most promising candidates which may show financial return in 3-5 years The replacement of fossil fuel with hydrogen in the automotive industry offers a substantial reduction of the harmful environmental effects however it is still the most challenging because of the absence of the hydrogen infra structure the price and the lifetime of the fuel cell (FC) engine and the unsuitable regulations as well In this work a new possible market was identified and analyzed in different points of view This market segment is a car sharing system operating with small urban vehicles which not only can solve some environmental problems (e g air pollution and CO(2) emission) but also helps to reduce congestion secure energy supply and ease its distribution First a sensitivity analysis was done and the key performance indicators of the system were determined The financial return of a hydrogen based car sharing system was examined carefully as a function of the rated power of the fuel cell power train the way of hydrogen supply the cost of the hydrogen and the size of the car fleet Finally a possible hydrogen based car sharing service was designed and optimized to the down town of Budapest Hungary A sustainable system was proposed which can satisfy the needs of the business (i e profitability) and the environment (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved