Aerogel materials exhibit superior thermal insulation characteristics due largely to their highly porous internal structure. A recently developed class of montmorillonite clay-based aerogels provides the attractive thermal properties of traditional aerogel materials using constituents that are chemically benign and abundantly available. Results are compared for aerogels made from clay alone and those with polyvinyl alcohol introduced during processing. Results demonstrate that as well as strength advantages, the addition of the polymer also leads to a reduction in thermal conductivity. Experimental thermal conductivity data as well as a model to describe the mechanisms involved in impeding thermal transport are presented. (C) 2008 Elsevier Ltd. All rights reserved.