Efficient on-board hydrogen storage for fuel cell vehicles is one of the most challenging problems associated with the use of hydrogen as a transportation energy carrier. Hydrides of light metals can have both high gravimetric and volumetric hydrogen densities, making them good candidates for mobile storage technologies. Unfortunately, existing hydrides are either thermodynamically or kinetically unacceptable for use in vehicular hydrogen storage systems. New complex hydrides are being discovered experimentally, but a fast method for screening the thermodynamics of potential hydrides is needed to guide experiments. In this talk I show that first principles quantum mechanical methods can be used to screen a large number of potential hydrogen storage materials. These methods can give estimates of the thermodynamics of hydrogen release, the effects of nanoparticle sizing and doping on thermodynamics, and the kinetics of surface poisoning.