The invention is directed to an ORC (Organic Rankine Cycle) system at least partially co-generative for the production of electric energy and the heating of a fluid. The system includes at least two regenerative exchangers positioned in series on the route of the work fluid between the exit of an electric expander-generator group and the entrance of a condenser of the ORC system, and a heat exchanger-user connected by means of an offtake line to at least one of said regenerative exchangers to receive from them a part of the capacity of work fluid and crossed by the user fluid to be heated by means of a thermal exchange with said capacity of work fluid. A part of the capacity of the work fluid on exiting from the user exchanger is returned to the same regenerative exchanger.