Metal organic framework UiO-66 has high chemical and thermal stability. However, it is difficult to produce such Zr-based MOFs with good crystalline morphology. Here, highly pure metal organic framework UiO-66 has been synthesized at low temperature (50 degrees C). The as-synthesized sample has been characterized by X-ray diffraction, thermogravimetric analysis, nitrogen adsorption, and scanning electron microscopy. Its hydrogen-storage capacity has been measured by means of an Intelligent Gravimetric Analyser. The results showed that UiO-66 was synthesized in octahedral crystals of well-defined sizes (150-200 nm) and had a high specific surface area (1358 m(2)/g). The as-synthesized UiO-66 showed a significant hydrogen uptake even at a moderate pressure, which increased to 3.35 wt% at 77 K and 1.8 MPa. A grand canonical Monte Carlo simulation (GCMG) has been employed to calculate the adsorption of hydrogen in UiO-66. The result of this simulation provided a theoretical foundation for the experimental results. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.