On March 23, 1989, while Pons was the chairman of the chemistry department at the University of Utah, he and Martin Fleischmann announced the experimental production of "N-Fusion", which was quickly labeled by the press cold fusion. After a short period of public acclaim, hundreds of scientists attempted to reproduce the effects but generally failed. After the claims were found to be unreproducible, the scientific community determined the claims were incomplete and inaccurate.
Pons moved to France in 1992, along with Fleischmann, to work at a Toyota-sponsored laboratory. The laboratory closed in 1998 after a £12 million research investment without conclusive results. He gave up his US citizenship and became a French citizen.