Heterogeneous catalytic acetylation of benzo-15-crown-5 was investigated using solid Lewis acids consisting of sulfated zirconia calcined at 625 degrees C or K10 exchanged by Cu, Zn, Fe or Sn ions and treated at 250 degrees C. The nature of the transition metal ions introduced in the mesoporous clay plays an important role in the activity of the catalysts. Sn-exchanged K10 shows the best catalytic properties and could suit for practical preparative purposes. 4'-Acetyl-benzo-15-crown-5 was produced with 90% yield under optimal conditions.