The fueling of hydrogen vehicles in three minutes enabling ranges above 500 km offers a significant advantage over other types of electric powertrain vehicles. SAE J2601, published in 2010, offers the first and only worldwide guideline to standardize fueling methodology. Due to the properties of hydrogen and compressed storage, each type and geometry tank heats up differently. Therefore, a hydrogen fueling methodology needs to take into account the range of storage anticipated from all automakers. This paper will describe a simulation tool developed in order to be able to assist in the development of a fueling procedure for General Motors Company; SAE J2601 team and the validation thereof.A reduced numerical simulation model has been developed that simulates the thermal response of a compressed gas storage tank operated under transient conditions. The stored gas is represented as a lumped mass with a spatially uniform temperature and pressure distribution inside the cylinder; a real gas model is employed to calculate the gas properties. The heat transfer through the cylinder wall is modeled by one-dimensional heat conduction in radial direction. The heat transfer coefficient from stored gas to the inner cylinder wall was provided by detailed three-dimensional transient computational fluid dynamics (CFD) simulations. These CFD simulations resolved all solid material layers as well the gas volume utilizing a real gas model. An instrumented tank with thermocouples inside both gas and cylinder walls was built and tested over a wide range of operating conditions to evaluate the quality of the simulation results. The test series included refueling and defueling at hydrogen gas flow rates ranging from 0.5 to 30 g/s at ambient temperatures from -40 to +40°C. The reduced simulation model predicts the average gas temperature evolution during refueling to an accuracy of approximately 1°C.