This paper presents details of a hydrogen fuelled, internal combustion engine under development at the University of Melbourne. Favorable and unfavorable properties of hydrogen as a combustion engine fuel have been accommodated in a design of a fuel efficient and clean engine providing similar to gasoline maximum torque and power. The advanced H2ICE being developed is a modified version of the Ford of Australia turbocharged, gasoline, 4 liter, in-line, six-cylinder engine fitted with port hydrogen gas fuel injectors and the hydrogen assisted jet ignition (HAJI) system. The combustion chamber (cylinder head and piston shape) is redesigned to produce an increased compression ratio and therefore a better fuel efficiency. Two gas fuel injectors are used for each cylinder to provide the amount of fuel needed. The fixed geometry turbocharger is replaced by a variable geometry turbocharger for a better efficiency over the wide range of operational load and engine speed. Thanks to the combustion properties of hydrogen further enhanced by the HAJI injection system, the engine is run throttless reducing the load by simply increasing the air to fuel ratio (quality governing as in a diesel engine). The computational model developed for addressing the major design issues and details of this design are presented. Engine performance and efficiency maps are included.