To obtain a porous ceramic composite member having a narrow pore diameter distribution giving excellent penetrability and excellent selectivity on the separation of H2, CH4 and O2 from a gas mixture by binding a silicone alkoxide or chloride having organic functional groups to silica-zirconia composite substrate in its fine pores through siloxane bonds and subsequently oxidizing the obtained siloxane-bound product to integrally bind the product to the inner walls of the fine pores.

This porous ceramic composite member is obtained by subjecting an organic group-having silicone alkoxide or chloride of the formula {R, R' and R" are each hydrogen or a hydrocarbon group; X is OCnH2n+1 [(n) is an integer of 1-4] or Cl} to a substitution reaction in the fine pores of silica- zirconia composite substrate containing the zirconium in an amount of ≤0.5 fold mole that of the total silicon and subsequently oxidizing the obtained siloxane-bound product to integrally bind the product to the inner walls of the fine pores.