AFC said the project with INEOS ChlorVinyls would use surplus hydrogen from the chemical firm's Runcorn facility in northwest England to supplement the plant's energy needs.
INEOS's website says the plant has energy needs comparable to those of a city the size of Liverpool and aims to reduce its reliance on fossil fuels by generating 20 percent of energy requirements from renewable resources.
AFC, which estimates that the chlor-alkali industry consumes 1 percent of the world's energy, has already installed its hydrogen harnessing technology at Dutch group Akzo Nobel's Bitterfeld site in Germany.
After initial delays, AFC said in July that it had tested the first installation and that it was working toward full commercial operation.
"This is a significant step for AFC Energy," said AFC's managing director Ian Balchin. "Having successfully demonstrated an AFC Fuel Cell system using industrially produced hydrogen, we are able to work with new partners."
AFC did not say how much the INEOS deal was worth, when the technology was likely to enter operation at the Runcorn site or how much electricity would be generated from the plant.
AFC shares, which are worth more than seven times what they were at the start of the year and have risen over 60 percent just recently.
While back at levels set in early 2008, the stock is still short of highs set in 2007.