Abstract: Apparatus for condensing vapors of subliming substances. The apparatus comprises a vessel having gas permeable porous walls spaced within a heated jacket, an inlet for supplying the gas mixture to be condensed into the interior of said vessel, an outlet for passing the non-condensed portion of said gas mixture together with solid condensate from said vessel, inlets into the space between the inner jacket wall and said vessel, means for supplying said space with a gas permeating through said gas permeable porous walls into said vessel, nozzles for injection of a liquid spray into the interior of said vessel, a filtering system, outlets for withdrawing non-condensed portion of said gas mixture, a receptacle for accumulating the solid condensate, and means for removing the solid condensate.