Recent experimental and modeling studies have suggested that metal-organic frameworks (MOFs) may be promising materials to meet desired targets for hydrogen storage. MOFs have extremely high surface areas, up to 5000 – 6000 m2/g, which should prove beneficial. However, the heats of adsorption are low, and consequently, the amount of hydrogen adsorbed at room temperature is low. The heat of adsorption generally increases for smaller pores, for example from interpenetrated structures, but there is a cost in terms of free volume available for hydrogen. Another strategy for increasing the heat of adsorption is to change the chemical nature of the MOF walls and corners. In this work, we performed classical atomistic simulations in which we artificially increased the heat of adsorption by modifying the framework Lennard-Jones parameters. Adsorption isotherms were calculated by grand canonical Monte Carlo simulation with these modified parameters. The results provide guidelines for how much the heat of adsorption must be increased for a given framework structure in order to meet the DOE targets for hydrogen storage. From the results, we developed a graph showing the heats of adsorption that must be attained as a function of the MOF free volume in order to meet the target levels of adsorption. In addition, we have performed electronic structure calculations for cation-containing MOFs to investigate how increased electric fields may increase the heat of adsorption.