The Energy Catalyzer is an apparatus built by inventor Andrea Rossi, with support from his scientific consultant, physicist and emeritus professor Sergio Focardi. The 2009 patent application claims "a method and apparatus for carrying out nickeland hydrogen exothermal reactions," with production of copper. Although the patent cites previous works on cold fusion,one statement by Rossi asserted that it is not cold fusion, but rather LENR, Low-Energy Nuclear Reaction. A similar system, but yielding considerably less power, had previously been described by Focardi et al.
For further info about the E-Cat I now refer to the English Wikipedia-page