This paper discusses the development of an electronically controlled gas injection system for a hydrogen-fuelled spark ignition engine. In view of its typical combustion characteristics the mode of fuelling plays a critical role for practical operation of a hydrogen engine. The system developed should have adequate flexibility to provide the appropriate mixture into the engine at the appropriate point in the engine cycle operation. The present work describes in detail the design considerations of an electronically controlled solenoid actuated injection system. Conditions leading to smooth operation of the engine could be achieved without any problem of backfire, knocking or rapid rate of pressure rise. The performance and emission characteristics of the engine were determined under various operating conditions. (C) 2000 International Association for Hydrogen Energy.