Hydrogen management will be a critical issue for refiners as a result of the 1990 Amendments to the U.S. Clean Air Act. The problem stemsfrom a reduction in hydrogen production and an increase in consumption. The addition of oxygenates to gasoline, as mandated for certain geographic areas at certain times of the year, will mean that less octane is required from the reformer, lowering the severity of the operation, and hence, the amount of hydrogen formed. Also the mandate reducing aromatics content to 25 per cent (20 per cent by proposed California state reg_,'__tions)will result in a further reduction of reformer operating severity, hence, severely reducing hydrogen production. Another contribution to the problem in managing hydrogen results from increased hydrogen consumption to meet benzene specifications, reduced T90, and lower sulfur levels in diesel. To exacerbate the problem, as heavier crudes are introduced to the refinery, the importance of catalytic hydroprocessing will increase. Hydroprocessingcan be a hydrogen guzzler. In August 1990 the U.S. Environmental Protection Agency (EPA) anno_._nced that it is taking steps to cut the sulfur content of diesel fuel by 80 per cent-from 0.25 weight per cent to 0.05 weight per cent-effective October 1, 1993. In addition, the level of aromatics in diesel fuel has been the topic of several regulatory efforts in California and by the federal government. However, there exists some question o_ whether the proposed maximum aromaticscontent can be achieved and whether the aromatics content decreases concomitantly with decreases in sulfur content due to increased severity of processing conditions. In NIPER topical report NIPER-468,