Several Bronsted acidic ionic liquids (BAILS) were synthesized and used as catalysts for the cyclotrimerization of propanal. The acidity of different BAILS was explored and a preliminarily study of the relationship between catalytic activity and acidity was performed. The kinetics for the BAILs-catalyzed cyclotrimerization of propanal was studied systemically to determine the kinetic model and the kinetic parameters by taking [BSTMG][HSO4] as the representative catalyst. The effects of various parameters such as catalyst loading, reaction temperature on the kinetics were examined in detail. Besides, the structures of three representative BAILs and the interactions between propanal molecule and ionic pairs of BAILs were studied by means of quantum chemistry calculations. (C) 2013 Elsevier B.V. All rights reserved.