This invention relates to a new system for controlling temperature and pressure in, at least, one chemical reactor, characterized in that it includes, at least, the following devices: a) a deposit with at least one pressure regulation device; b) a connecting duct between said deposit and the reactor; c) a device for injecting condensates into the reactor. Moreover, the invention relates to the use of said control system to control the pressure and temperature of at least one chemical reactor, being especially applicable to a chemical reactor in which a hydrothermal biomass carbonization reaction takes place.