The influence of grafting temperature on Al-grafted MCM-41 catalysts prepared by reacting pure silica MCM-41 with aqueous solutions containing Al polycations was investigated by performing the alumination at room temperature (RT) or 80 degrees C, Better retention of structural integrity was achieved at 80 degrees C than at RT, and incorporation of Al was up to four times higher at 80 degrees C. The higher Al content of materials grafted at 80 degrees C translated to higher acid content and higher total conversions for the dealkylation of cumene. However, the catalytic activity per active site (TOF values) was higher for RT-grafted materials presumably due to better site isolation,