A simple modification, methylation of the nitrogen-substituted mesoporous silica SBA-15, enhances the basicity of a solid-base catalyst. The methyl group donates an electron to the nitrogen atom in the silica framework. This catalyst accelerates Knoevenagel condensation using benzaldehyde and diethyl malonate, which conventional solid-base catalysts reported to date cannot do. This report demonstrates a possible new type of base catalyst using nitrogen-substituted mesoporous silica materials.