Metal-organic frameworks (MOFs) have been increasingly studied as potential materials for natural gas storage, but inconsistencies in reporting high-pressure adsorption data and a lack of comparative studies have made it difficult to evaluate their performance. This review discusses high-pressure adsorption measurements and recent efforts to develop MOFs with high methane storage capacities. Six MOFs and an activated carbon, with a range of surface areas, pore structures, and surface chemistries, were evaluated in detail. High-pressure methane adsorption isotherms were used to compare gravimetric and volumetric capacities, isosteric heats of adsorption, and usable storage capacities. The importance of increasing volumetric capacity, rather than gravimetric capacity, for extending the driving range of natural gas vehicles was highlighted. Other factors, such as thermal management, mechanical properties, and the effects of impurities, were also considered. Natural gas, mainly composed of methane, has the potential to replace petroleum as the primary fuel for transportation due to its lower emissions and higher efficiency. However, its volumetric energy density is low, and compression or liquefaction are costly and unsuitable for light-duty vehicles. Adsorbents offer a promising alternative for storing natural gas at ambient temperature and moderate pressures, allowing the use of inexpensive fuel tanks and single-stage compressors. Activated carbons have been the most studied materials for this purpose, but their capacities are still below those of compressed natural gas (CNG). MOFs, with their high porosity and tunable pore surfaces, have shown promise in achieving higher methane storage capacities. High-pressure adsorption measurements are crucial for evaluating adsorbents for natural gas storage, but inconsistencies in reporting data and the complexity of high-pressure experiments make comparisons challenging. The terms excess, total, and absolute adsorption are often used interchangeably, leading to confusion. The total adsorption, which includes all gas molecules within the pores, is often used as an approximation for absolute adsorption. Accurate measurements of high-pressure adsorption isotherms are essential for determining the performance of materials. The study evaluated six MOFs and an activated carbon, finding that HKUST-1 has the highest usable volumetric capacity for methane. The usable capacity is defined as the amount of methane that can be delivered when decreasing from the adsorption pressure to a specific desorption pressure. HKUST-1's lower interaction with methane compared to Ni2(dobdc) results in a higher usable capacity. The optimal binding enthalpy for methane adsorption at 35 bar and desorption at 5 bar is -17 kJ mol⁻¹, which matches that of HKUST-1. This highlights the importance of both increasing capacity and optimizing binding enthalpy when designing improved adsorbents. While increasing capacity is crucial, the density of adsorption sites with optimal binding enthalpy must also be considered. Overall, HKUST-1 appears to be the most promising MOF for natural gas storage.Metal-organic frameworks (MOFs) have been increasingly studied as potential materials for natural gas storage, but inconsistencies in reporting high-pressure adsorption data and a lack of comparative studies have made it difficult to evaluate their performance. This review discusses high-pressure adsorption measurements and recent efforts to develop MOFs with high methane storage capacities. Six MOFs and an activated carbon, with a range of surface areas, pore structures, and surface chemistries, were evaluated in detail. High-pressure methane adsorption isotherms were used to compare gravimetric and volumetric capacities, isosteric heats of adsorption, and usable storage capacities. The importance of increasing volumetric capacity, rather than gravimetric capacity, for extending the driving range of natural gas vehicles was highlighted. Other factors, such as thermal management, mechanical properties, and the effects of impurities, were also considered. Natural gas, mainly composed of methane, has the potential to replace petroleum as the primary fuel for transportation due to its lower emissions and higher efficiency. However, its volumetric energy density is low, and compression or liquefaction are costly and unsuitable for light-duty vehicles. Adsorbents offer a promising alternative for storing natural gas at ambient temperature and moderate pressures, allowing the use of inexpensive fuel tanks and single-stage compressors. Activated carbons have been the most studied materials for this purpose, but their capacities are still below those of compressed natural gas (CNG). MOFs, with their high porosity and tunable pore surfaces, have shown promise in achieving higher methane storage capacities. High-pressure adsorption measurements are crucial for evaluating adsorbents for natural gas storage, but inconsistencies in reporting data and the complexity of high-pressure experiments make comparisons challenging. The terms excess, total, and absolute adsorption are often used interchangeably, leading to confusion. The total adsorption, which includes all gas molecules within the pores, is often used as an approximation for absolute adsorption. Accurate measurements of high-pressure adsorption isotherms are essential for determining the performance of materials. The study evaluated six MOFs and an activated carbon, finding that HKUST-1 has the highest usable volumetric capacity for methane. The usable capacity is defined as the amount of methane that can be delivered when decreasing from the adsorption pressure to a specific desorption pressure. HKUST-1's lower interaction with methane compared to Ni2(dobdc) results in a higher usable capacity. The optimal binding enthalpy for methane adsorption at 35 bar and desorption at 5 bar is -17 kJ mol⁻¹, which matches that of HKUST-1. This highlights the importance of both increasing capacity and optimizing binding enthalpy when designing improved adsorbents. While increasing capacity is crucial, the density of adsorption sites with optimal binding enthalpy must also be considered. Overall, HKUST-1 appears to be the most promising MOF for natural gas storage.