Amino-functionalized MCM-41 was synthesized via direct condensation, as well as post-grafting, using 3-aminopropyltrimethoxysilane as the functionalization agent. Keggin and Preyssler-structured heteropolyacids (HPAs) were anchored on the surface of amino-functionalized MCM-41 by chemically bonding to amino groups. HPAs directly supported on MCM-41 by impregnation were also prepared for comparison. These catalysts were characterized by Infra-red spectroscopy, X-ray diffraction, N-2-adsorption, Hammett indicator and UV-Vis spectroscopy, and evaluated in esterification of n-butanol with acetic acid. HPAs anchored on amino-functionalized MCM-41 via condensation give very stable and substantially higher activity than the ones via grafting. In contrast, MCM-41 supported HPA catalysts prepared by direct impregnating lose their catalytic activities rapidly due to the leaching of HPA active sites. The catalyst activity is discussed in relation with physicochemical properties.