Abstract: A process for the production of a porous organic material, in particular an organic semi-permeable membrane, provided with a plurality of separate passageways, comprising dissolving a polymer in a solvent, using a drawplate comprising needles having a shape conjugate with that of the passageways and external dimensions comprising between 0.7 and 1.2 times those of said passageways and an extrusion orifice of a conjugate fome to that of the extrudate and of internal dimensions comprising between 0.8 and 1.2 times those of said extrudate, injecting around the needles a solution having a viscosity greater than 500 millipascal-second, introducing into the interior of the conduits of the drawplate a centering fluid which is a non-solvent with respect to the polymer and able to precipitate the polymeric solution, causing the extrudate to travel from the output of the drawplate a distance da in a gaseous atmosphere which is non-precipitating with respect to the polymeric solution such that 500.times.e<da<0.