Three types of reactions were observed on alkali exchanged A, X and Y zeolites during the vapour phase reaction of methanol with acetone : the methylation of acetone followed by dehydrogenation to form methyl vinyl ketone (MVK); the Meerwein-Ponndorf-Verley (MPV) reaction between acetone and methanol, coupled with the further dehydration to form propene and formaldehyde; and the condensation of acetone followed by further decomposition to form isobutene. The last two kinds of reactions are the main reactions on LiX and NaX, which possess a relatively strong Lewis acidity. When Lewis basicity increases and Lewis acidity decreases, these two reactions are dramatically depressed, which results in an increase in selectivity to MVK. After high energy milling the zeolite becomes amorphous with no change in chemical composition. The catalytic results over these materials also revealed an increase in the production of MVK and the depressing of the other two reactions. This change is attributed to the crush of the zeolite pore structure, which is another factor affecting the product distribution.