Rapid exhaustion of fossil fuel, exponential increase of automotive vehicles and stringent emission norms force the researchers to find out an alternative fuel which can be used in diesel engines with less modification or without any modification. The present paper reviews the effect of using hydrogen as a fuel in diesel engine. In this review, the investigations done by the researchers were categorized into three forms. First one was inducting hydrogen into diesel engine by the way of carburetion, second one wasinducting hydrogen into diesel engine by the way of manifold and port injection and third one was inducting hydrogen into diesel engine by the way of in-cylinder injection. In all the categories, the data of diesel fuel operation was taken as a base line configuration to examine the effectiveness of the diesel-hydrogen dual fuel combustion.The review showed that the use of hydrogen as a fuel in a diesel engine, keep the combustion temperaturehigh and increases NOXemission and reduces smoke emission. It may be concluded that hydrogen is one of the fuels of future. © 2015, Sphinx Knowledge House. All rights reserved.