A bifunctional catalyst containing both the hydrophobic methyl and hydrophilic sulfonic acid groups has been successfully fabricated by mild surface modification of the pre-prepared silica nanoparticles. To its credit, the methyl groups in the catalyst were applied to improve the surface wettability of silica solid nanoparticles, while the sulfonic acid groups were devoted to catalyzing the deacetalization of various acetal derivatives. The catalyst was characterized in detail by Scanning electron microscope (SEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR) and Thermogravimetric analysis (TGA). The catalytic results revealed that the bifunctional SiO2-Me&SO3H NPs exhibited superior activity for the deacetalization of 4-methoxybenzaldehyde dimethyl acetal and the product conversion could be >99% within 45 min in the toluene/water biphasic system. The main reason was probably due to the formation of Pickering emulsion, which could greatly improve the interface area between the oil and water and decrease the mass transfer resistance. (C) 2015 Elsevier B.V. All rights reserved.