It has been shown that alpha-methylstyrene in the presence of H-HSZ (SiO2/Al2O3 = 40-120) and Fe-HSZ (SiO2/Al2O3 = 60) pentasils in a nitrogen atmosphere (80-120 degrees C, 5-20 wt % catalyst) is converted into linear (4-methyl-2,4-diphenylpent-1-and -2-enes) and cyclic (1,1,3-trimethyl-3-phenylindan) dimers. The H-type high-silica (SiO2/Al2O3 = 120) and ferrosilicate zeolites in air facilitate the conversion of alpha-methylstyrene into acetophenone and alpha-phenylpropionaldehyde.