Process to transform biomass into hydrochar by means of a plant comprising: - a first reactor, a second reactor, a third reactor into which feedstock can be loaded from the outside and the process products can be unloaded from the plant to the outside; - a fourth reactor, a fifth reactor and a sixth reactor in which the transformation of biomass into hydrochar can take place at a process temperature between 180°C and 250°C, at a process pressure corresponding or higher than the vapor tension of water at the process temperature, namely between 15 bar and 30 bar, in a time span equal to the reaction time between 3 and 8 hours; - a heat exchanger through which the first reactor, the second reactor, the third reactor are indistinctly connected to the fourth reactor, the fifth reactor and the sixth reactor; - the first reactor, the second reactor, the third reactor, the fourth reactor, the fifth reactor and the sixth reactor being connected to one another also directly; the process providing at the initial state that: - the first reactor is full of process products, is pressurized at the process pressure and at an unloading temperature between 30°C and 50°C; - the second reactor is full of feedstock and is pressurized at the process pressure; - the third reactor is empty and is pressurized at the process pressure; - the fourth reactor is full of process products, is pressurized at the process pressure and is at a reaction temperature; - the fifth reactor is empty and is pressurized at a process pressure; - the sixth reactor is full of feedstock, is pressurized at the process temperature and is partially heated at a temperature between 160°C and 210°C; the process providing a first cycle in which, simultaneously: - the first reactor, in succession, is isolated from the rest of the plant, is depressurized at the atmospheric pressure, is emptied of the process products contained in it, is loaded with feedstock, and is, finally, pressurized at the process pressure; - the process products contained in the fourth reactor are transferred into the third reactor passing through the heat exchanger in countercurrent with the feedstock passing through the heat exchanger which is transferred from the second reactor to the fifth reactor, so as to transfer heat from the process products to the feedstock; - the air contained in the third reactor and the fifth reactor is transferred into the second reactor and the fourth reactor, respectively; - in the sixth reactor, the feedstock is brought to the reaction temperature, and the reaction as well as the transformation into process products take place. - a first reactor, a second reactor, a third reactor into which feedstock can be loaded from the outside and the process products can be unloaded from the plant to the outside; - a fourth reactor, a fifth reactor and a sixth reactor in which the transformation of biomass into hydrochar can take place at a process temperature between 180°C and 250°C, at a process pressure corresponding or higher than the vapor tension of water at the process temperature, namely between 15 bar and 30 bar, in a time span equal to the reaction time between 3 and 8 hours; - a heat exchanger through which the first reactor, the second reactor, the third reactor are indistinctly connected to the fourth reactor, the fifth reactor and the sixth reactor; - the first reactor, the second reactor, the third reactor, the fourth reactor, the fifth reactor and the sixth reactor being connected to one another also directly; the process providing at the initial state that: - the first reactor is full of process products, is pressurized at the process pressure and at an unloading temperature between 30°C and 50°C; - the second reactor is full of feedstock and is pressurized at the process pressure; - the third reactor is empty and is pressurized at the process pressure; - the fourth reactor is full of process products, is pressurized at the process pressure and is at a reaction temperature; - the fifth reactor is empty and is pressurized at a process pressure; - the sixth reactor is full of feedstock, is pressurized at the process temperature and is partially heated at a temperature between 160°C and 210°C; the process providing a first cycle in which, simultaneously: - the first reactor, in succession, is isolated from the rest of the plant, is depressurized at the atmospheric pressure, is emptied of the process products contained in it, is loaded with feedstock, and is, finally, pressurized at the process pressure; - the process products contained in the fourth reactor are transferred into the third reactor passing through the heat exchanger in countercurrent with the feedstock passing through the heat exchanger which is transferred from the second reactor to the fifth reactor, so as to transfer heat from the process products to the feedstock; - the air contained in the third reactor and the fifth reactor is transferred into the second reactor and the fourth reactor, respectively; - in the sixth reactor, the feedstock is brought to the reaction temperature, and the reaction as well as the transformation into process products take place.