New methods have been demonstrated for the synthesis of high surface area cation-substituted hexaaluminates. These materials hold promise for use as catalysts in high temperature combustors. The hexaaluminates were prepared by calcining high surface area aerogels at temperatures up to 1600 degrees C. In comparing unsubstituted and cation-substituted hexaaluminates, we found that phase transformations for the cation-substituted materials were more direct. Small amounts of BaCO3 and BaAl2O4 were observed during transformation of the unsubstituted materials, while the cation-substituted materials transformed directly from an amorphous phase to crystalline hexaaluminate. The presence of substitution cations also caused the transformation to occur at lower temperatures. Manganese appears to be a better substitution cation than cobalt since BaMnAl11O19-alpha exhibited higher surface areas and methane combustion reaction rates than BaCoAl11O19-alpha. A doubly substituted material, BaMn0.5Co0.5Al11O19-alpha, was more active than its singly substituted counterparts. This result suggests a synergy between Mn and Co in the barium hexaaluminates.