Porous hybrid molybdic acid/rhodamine B (RhB) aggregates with various morphologies were prepared on porous anodic alumina (PAA) templates via a self-aggregation reaction in a molybdic acid/RhB colloidal solution. The results indicate that our method can easily prepare porous hybrid molybdic acid/RhB aggregates under the influence of PAA templates at low temperature in mild reaction conditions. Using the porous properties of the molybdic acid/RhB aggregates, a porous "sandwich-like" gas-sensor prototype was fabricated, which shows gas-sensing properties to ethanol, ammonia and ozone by changing its electrical resistance at room temperature. The gas sensitivity of the molybdic acid/RhB aggregates based on the integration of the individual molybdic acid/RhB aggregate was discussed. Our method may be a strategy for fabricating porous organic/inorganic hybrid functional materials at low cost and constructing microdevices using the porosity of both the aggregates and the anodic alumina membrane. (C) 2009 Elsevier B.V. All rights reserved.