Microporous titanosilicate (K2TiSi3O9 center dot H2O) with an umbite structure has been reproducibly prepared as 5-mu m-thick continuous membranes on asymmetric TiO2 tubular supports by seeded hydrothermal synthesis. These membranes were able to separate H-2 from N-2 with good selectivity even in the presence of moisture, unlike other microporous zeolitic hydrophilic membranes where capillary condensation strongly hinders gas permeation. The average H-2/N-2 separation selectivity calculated for five Ti-umbite membranes obtained in the same synthesis conditions (200 degrees C, 48 h) was 45.2 +/- 3.8 (together with an average H-2 permeance of 4.6 +/- 11.1 x 10(-9) mol/(m(2) s Pa). (c) 2008 Elsevier B.V. All rights reserved.