The invention provides a pyrolysis reaction system, the system comprising: a pyrolysis chamber comprising a feed inlet, a gas inlet and a product outlet, wherein the pyrolysis chamber is configured i) to receive a pyrolysable organic feed and an inert gas via the feed inlet and gas inlet respectively, ii) to pyrolyse the organic feed at a pyrolysis temperature to produce a carbonaceous pyrolysis product and a pyrolysis gas, wherein the pyrolysis gas will combine with the inert gas to form a gas mixture having a pyrolysis chamber pressure in the pyrolysis chamber, and iii) to discharge the carbonaceous pyrolysis product via the product outlet; a gas reactor configured to react the pyrolysis gas by combustion and/or carbon deposition at a gas reaction temperature and a gas reactor pressure; and a first partition defining a boundary between the pyrolysis chamber and the gas reactor, the first partition comprising a plurality of first apertures to provide fluid communication between the pyrolysis chamber and the gas reactor, wherein the pyrolysis reaction system is operable with the gas reactor pressure less than the pyrolysis chamber pressure such that the gas mixture flows from the pyrolysis chamber to the gas reactor through the first apertures, thereby providing at least a portion of the pyrolysis gas for reaction in the gas reactor.