Initial observations from permeation experiments are reported for a class of novel membranes which display potential in the area of high temperature (similar to 900 K) gas separations. The existence of these membranes was first postulated from theoretical studies on transport of gases through ultra-thin (similar to 5-25 mu), nanoporous silica. The experimental results presented here confirm these observations, as demonstrated by membranes produced with kinetic selectivities for carbon dioxide/nitrogen greater than 75:1 at 873 K. (c) 2005 Elsevier B.V. All rights reserved.