The study of permeable composite monolith (PCM) membranes for the Fischer-Tropsch synthesis is continued. On the scale of membranes with outer diameter of 42 mm, it is proved that PCM can combine high productivity of hydrocarbons (> 55 kg(C5+) (m(PCM)(3) h)(-1) 0.6 Mpa, 484 K), high selectivity towards heavy hydrocarbons (alpha(ASF) > 0.85, C5+ upto 0.9) as well as high heat-conductivity and high mechanical strength. (c) 2005 Elsevier B.V. All rights reserved.