In this paper, we explore the catalytic activity of SiO₂ nanoparticles (NPs) as an eco-friendly, efficient and reusable catalyst in the synthesis of 2,3-dihydro-1H-perimidines as well as tetraketones. For tetraketones syntheses, a simple tandem Knoevenagel condensation following Michael addition procedure is performed by the reaction between benzaldehydes and 5,5-dimethyl-1,3-cyclohexanediones under solvent-free condition using SiO₂ NPs as an efficient solid catalyst. In addition, for 2,3-dihydro-1H-perimidines syntheses, cyclocondensation of various aldehydes with 1,8-diaminonaphthalene is achieved under solvent-free condition using SiO₂ NPs as a catalyst at room temperature. The results showed catalytic enhancement in both synthetic procedures.In this work,4-(2,3-dihydro-1H-perimidin-2-yl)benzonitrileand2-(pyridin-4-yl)-2,3-dihydro-1Hperimidine are synthesized as new compounds. Also, reusability study of SiO₂ NPs was done to ensure its applicability as a recycled catalyst in this work.