Indirect Selective Laser Sintering procedure for the fabrication of monolithic systems of carbonaceous or ceramic nature, characterized in that it comprises the following stages: i) preparing a dry homogeneous mixture of a starting base material selected from a ceramic or carbonaceous material with a phenol-formaldehyde resin selected from the group consisting of a novolac resin or a resol resin, where the ratio between said starting base material and said resin is comprised between 95/5 - 60/40 for a ceramic material and between 90/10 - 10/90 for a carbonaceous material; ii) in a selective laser sintering machine, sintering said homogeneous mixture until forming a part or preform called "green body" with the desired geometry; iii) next, removing the part, preform or "green body" from the sintering machine, cleaning it and performing a curing treatment at a temperature comprised between 150 and 300°C, so that a cured part, cured preform or cured green body is obtained; iv) performing a pyrolysis treatment of said cured green body in an inert atmosphere at a temperature comprised between 400 and 1,000°C to decompose the resin and provide a treated part or "brown body" which has a carbon residue derived from the pyrolysis of the resin, said pyrolysis treatment comprising alternate stages of isothermal heating and of non-isothermal heating; and v) finally, activating the brown body with a thermal treatment in a reactive atmosphere to eliminate said carbon residue derived from the pyrolysis and provide the ceramic or carbonaceous monolith, where the conditions of reactive atmosphere and temperature are selected depending on the ceramic or carbonaceous starting base material as follows: - for a ceramic starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 450-900 - for a carbonaceous starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 250-450 CO 2 700-1,200 Steam 900-1,200 and, optionally, in the case that said starting material is ceramic, vi) thermally treating said ceramic monolith in a reactive atmosphere of oxygen, air or mixtures of oxygen and an inert gas at a temperature greater than 900oC so that a densification or a transformation of crystalline phases takes place. i) preparing a dry homogeneous mixture of a starting base material selected from a ceramic or carbonaceous material with a phenol-formaldehyde resin selected from the group consisting of a novolac resin or a resol resin, where the ratio between said starting base material and said resin is comprised between 95/5 - 60/40 for a ceramic material and between 90/10 - 10/90 for a carbonaceous material; ii) in a selective laser sintering machine, sintering said homogeneous mixture until forming a part or preform called "green body" with the desired geometry; iii) next, removing the part, preform or "green body" from the sintering machine, cleaning it and performing a curing treatment at a temperature comprised between 150 and 300°C, so that a cured part, cured preform or cured green body is obtained; iv) performing a pyrolysis treatment of said cured green body in an inert atmosphere at a temperature comprised between 400 and 1,000°C to decompose the resin and provide a treated part or "brown body" which has a carbon residue derived from the pyrolysis of the resin, said pyrolysis treatment comprising alternate stages of isothermal heating and of non-isothermal heating; and v) finally, activating the brown body with a thermal treatment in a reactive atmosphere to eliminate said carbon residue derived from the pyrolysis and provide the ceramic or carbonaceous monolith, where the conditions of reactive atmosphere and temperature are selected depending on the ceramic or carbonaceous starting base material as follows: - for a ceramic starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 450-900 - for a carbonaceous starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 250-450 CO 2 700-1,200 Steam 900-1,200 and, optionally, in the case that said starting material is ceramic, - for a ceramic starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 450-900 - for a carbonaceous starting base material: Reagent gas Temperature (°C) O 2, air or mixtures of O 2 and an inert gas 250-450 CO 2 700-1,200 Steam 900-1,200 vi) thermally treating said ceramic monolith in a reactive atmosphere of oxygen, air or mixtures of oxygen and an inert gas at a temperature greater than 900oC so that a densification or a transformation of crystalline phases takes place.