As a consequence of the heterogeneous active sites in fluorinated alumina surface, benzene propylation exhibits a complex reaction system, involving aromatic alkylation and propylene secondary reactions. From reaction results at different residence times, in some aluminas with different fluorine content, it was possible to find out the same reaction scheme for each family of hydrocarbons. A simplified kinetic model which relates the rate reaction constants of the aromatic alkylation with the olefin oligomerization let us compare the catalytic activity of these aluminas. We also attempted to study this heterogeneity using some characterization techniques: ammonia TPD and chemisorption. All of these results allowed us to figure out in the TPD chart which kind of acid sites could be responsible for the alkylation of benzene. (C) 2003 Elsevier Science B.V. All rights reserved.