Butylketene and hexylketene have been synthesized by catalytic dehydration of hexanoic and octanoic acids, respectively, over functionalized silica monoliths. The efficacy of silica for production of low molecular weight ketenes can be extended to higher molecular weight ketenes without any compromise in selectivity. For instance, the catalytic dehydration of octanoic acid was demonstrated to produce hexylketene with carbon selectivities on the order of 90% at temperatures between 745 and 795 K over a functionalized silica monolith. The results indicate that the control of contact time is a valid strategy for maximizing yield in catalytic ketene synthesis. Also, the ketene synthesis process can be integrated easily with ketene derivatization to prepare esters, in high yields. (c) 2005 Elsevier B.V. All rights reserved.