New solid acid catalysts based on silica-supported zinc triflate have been prepared for use in the rearrangement of alpha-pinene oxide to campholenic aldehyde. These catalysts exhibit considerable activity and can be recycled without loss of selectivity towards the aldehyde. The selectivity towards the aldehyde can be increased to 80% (at 50% conversion) when the reaction is performed at 25 degrees C using hexagonal mesoporous silica (HMS24) as the catalyst support.