A single cylinder hydrogen fuelled internal combustion engine was experimentally evaluated and a model was developed. The optimized hydrogen engine developed a peak power of 4.8 kW 3600 rpm while operating under lean conditions. Lean operation in the equivalence ratio range of 0.47-0.59 resulted in low NO. emissions. The spark timing, equivalence ratio, and fuel injection timing were optimized to achieve high torque and low NO. emissions for different engine speeds at wide open throttle. A one-dimensional model was developed for the single cylinder engine, which was able to predict the trends in brake torque, brake power, brake thermal efficiency and NO emissions for different engine speeds. It was found that the Woschni's correlation, which was originally developed for gasoline and diesel fuels under-predicted the convective heat transfer coefficient and the predicted coefficient was multiplied by a factor of 2.2 in order to simulate the actual heat losses with H-2 fuelled IC engines. This is due to the high burning velocity as well as a low quenching distance of hydrogen flame which presumably results in higher cooling losses in a hydrogen engine. Using the model, a sensitivity analysis was further performed to study the effect of operating conditions such as engine speed, spark timing and equivalence ratio on the performance parameters and NO. emissions. The model was able to predict the reported trends of an increase in torque and a maximum in exhaust NO concentration with an increase in the equivalence ratio. An increase in the exhaust NO. concentration with spark advance for all engines speeds was predicted. It was found that in order to achieve high torque, the spark energy must be provided closer to TDC for low speeds but should be advanced away from TDC for higher engine speeds. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.