A system is described that is capable of operating as an energy conversion system that functions as a fuel cell and generates electrical current from a fuel or fuels, or as a reactor for conversion of starter materials into more complex molecules through ion-ion and ion-molecules and which may preferably be adapted to operate as a gas to liquid (GTL) process. The system ionises at least one fuel or starter material and manipulates, selects and transports ions for reaction by means of suitable electrostatic or electrodynamic ion guides, filters or drift tubes. The system of the present application replaces the electrolyte, catalyst and/or membrane found in classic fuel cells or GTL processes with an electrostatic or electrodynamic ion manipulation region such as an ion guide, analyser, drift tube or filter.