The internal combustion engines have already become an indispensable and integral part of our present day life style, particularly in the transportation and agricultural sectors [Nagalingam B. Properties of hydrogen. In: Proceedings of the summer school of hydrogen energy, I IT Madras, 1984]. Unfortunately the survival of these engines has, of late, been threatened due to the problems of fuel crisis and environmental pollution. Therefore, to sustain the present growth rate of civilization, a nondepletable, clean fuel must be expeditiously sought. Hydrogen exactly caters to the specified needs. Hydrogen, even though "renewable" and "clean burning", does give rise to some undesirable combustion problems in an engine operation, such as backfire, pre-ignition, knocking and rapid rate of pressure rise [Srinivasa Rao P. Utilization of hydrogen in a dual fueled engine. In: Proceedings of the summer school of hydrogen energy, IIT Madras, 1984; Siebers DL. Hydrogen combustion under diesel engine conditions. Hydrogen Energy 1998;23:363-71]. The present investigation compares the performance and emission characteristics of a DI diesel engine with gaseous hydrogen as a fuel inducted by means of carburation technique and timed port injection technique (TPI) along with diesel as a source of ignition [Swain N, Design and testing of dedicated hydrogen-fueled engine. SAE 961077, 1996]. In the present study the specific energy consumption, NOx. emission and the exhaust gas temperature increased by 6%, 8% and 14%, respectively, and brake thermal efficiency and smoke level reduced by 5% and 8%, respectively, using carburation technique compared to baseline diesel. But in the TPI technique, the specific energy consumption, exhaust gas temperature and smoke level reduced by 15%, 45% and 18%, respectively. The brake thermal efficiency and NOx increased by 17% and 34%, respectively, compared to baseline diesel. The emissions such as HC, CO, and CO2 is very low in both carburation and TPI techniques compared baseline diesel. (C) 2007 Elsevier Ltd. All rights reserved.