Dealkylation of alkylnaphthalene, as a model of alkyl polycyclic aromatic hydrocarbon compounds in heavy oils, proceeded selectively on a silica monolayer solid acid catalyst. The activity was generated by the deposition of silica on alumina with generation of Bronsted acidity. The activity and Bronsted acid amount showed the maximum where the monolayer covered the surface, indicating that the Bronsted acid site generated on the silica monolayer was the active species. The activity and selectivity on the silica monolayer were high compared to other aluminosilicate catalysts, and high activity was observed even after calcination at 973-1173 K. (C) 2016 Elsevier B.V. All rights reserved.