In this work we predict the key adsorption properties for hydrogen storage applications by investigating a series of recently synthesized zirconium based MOFs. These MOFs consist of an inorganic brick (Zr6O4(OH)(4)(CO2)(12)) that binds to organic linkers (1,4-benzene-dicarboxylate and 4,4'-biphenyl-dicarboxylate) to form the two MOFs: UiO-66 and UiO-67. Particular attention has been paid to the performance of different classical force fields to describe the interactions between H-2 and the solid materials. It is found that combinations of several commonly used H-2 potentials in combination with the DREIDING force field give consistently good agreement with experimental adsorption data at 77 K, 95 K, and 110 K. The performance of the different force fields and hydrogen potentials is evaluated and discussed in terms of the physical interactions they describe. All tested force fields clearly underestimate adsorption at 296 K. Possible reasons for this discrepancy with experimental results are discussed and suggestions on how to improve the adsorption simulations are given.