By-product hydrogen generated in chemical complexes has been used as feedstock for other chemical and refinery processes, as a product for sale, and as fuel for boilers. The value of by-product hydrogen has increased along with concerns about the depletion of fossil fuels and environmental problems. Therefore, utilization of high-grade by-product hydrogen is required under these circumstances. Fuel cells, for which the technology has grown to nearly the level of commercialization, are a high-value way hydrogen can be used. In this study, a fuel cell power plant was modeled using certain assumptions and was assessed to demonstrate its economic feasibility as a potential method for using by-product hydrogen. An economic profitability standard was calculated for the base case and sensitivity and break-even analyses were done for key variables. Some cases considered future plans about support systems and variations in prices. Feed-in tariffs and the continuing development of fuel cell technologies were important to guarantee the profitability of the system. The trend toward higher prices was not favorable under the situation in which a feed-in tariff was applied but had an advantage under a no feed-in tariff condition. The results of a comparison among various hydrogen sources indicate that by-product hydrogen from chemical complexes has an economic advantage.