Metal-organic frameworks (MOFs) are highly attractive materials because of their ultra-high surface areas, simple preparation approaches, designable structures and potential applications. In this past several years, MOFs have attracted worldwide attention in the area of hydrogen energy, particularly for hydrogen storage. In this review, the recent progress of hydrogen storage in MOFs is presented. The relationships between hydrogen capacities and structure of MOFs are evaluated with emphasis on the roles of surface area and pore size. The interaction mechanism between H-2 and MOFs is discussed. The challenges to obtain a high hydrogen capacity at ambient temperature are explored.