Three series of mesoporous aluminosilicate (Al-MCM-41) samples were synthesized using different aluminum sources including aluminum isopropoxide, pseudo boehmite and aluminum sulfate. Their catalytic activities were tested in the conversion of aromatic hydrocarbons including hydrocracking of 1,3,5-triisopropylbenzene, alkylation of naphthalene, and hydrogenation of naphthalene and phenanthrene. The three series of Al-MCM-41 samples behaved differently in acting as acidic catalysts and as supports. The Al-MCM-41 synthesized using aluminum isopropoxide was found to be the most promising acidic catalyst and good support for Pt catalyst.