Composite structures are described that have a porous anodic oxide layer such as, for example, a porous anodic aluminum oxide layer. In one aspect, the present invention includes a composite gas separation module having a porous metal substrate; a porous anodic aluminum oxide layer, wherein the porous anodic aluminum oxide layer overlies the porous metal substrate; and a dense gas-selective membrane, wherein the dense gas-selective membrane overlies the porous anodic aluminum oxide layer. A composite filter is described having a porous non-aluminum metal substrate; and a porous anodic aluminum oxide layer, wherein the porous anodic aluminum oxide layer defines pores extending through the porous anodic aluminum oxide layer. Methods for fabricating composite gas separation modules and composite filters and methods for selectively separating hydrogen gas from a hydrogen gas-containing gaseous stream are also described.