A system is described for the pyrolysation and gasification of organic substances, in particular biomasses, comprising in cascade at least one evaporation module, at least one pyrolysis reactor and at least one gassing device, such evaporation module being supplied with the organic substance, to be dried and then be transferred through first supplying means in such pyrolysis reactor to be subjected to a pyrolysis process for producing at least one pyrolysis fuel syngas and remaining organic products, the remaining organic products being then transferred through second supplying means to such gassing device to produce at least one gasification fuel syngas, further comprising first channelling means for such pyrolysis fuel syngas and such gasification fuel syngas from such pyrolysis reactor to at least one energy user, second channelling means of burnt exhaust gases produced by such energy user towards such evaporation module, and third channelling means of such gasification fuel syngas from such gassing device to such pyrolysis module. A process is further described for the pyrolysation and gasification of organic substances through such system.