Abstract: The present invention relates to an energy conversion system and more particularly to the related apparatus and process. The system includes a reactor chamber having an input for a reactive substance supplied from a supply vessel, and means for receiving and transmitting a focused beam of electromagnetic or other radiation into the reactor itself. The reactor chamber is positioned with respect to means for collecting and focusing radiation, such as, electromagnetic radiation, such that a beam of focused radiation passes through the receiving and transmitting means provided in the wall of the reactor. The focused beam of radiation is, therefore, employed to induce a reactive substance to react to produce reaction products at high temperatures and elevated pressures. Advantageously, the reaction is reversible.