For the design of novel acid catalysts it is important to understand the principles of the generation of acidity. However, the origin of this acidity is unclear because the mixed solid‐acid usually possesses a complicated structure leading to different types of sites. The CVD of silica is being used on high surface area basic oxides to provide model compounds to elucidate the formation and functioning of acid catalysts. This paper reviews these studies and also shows how novel heat resistant catalysts can be obtained.