Sodium silicate from rice husk ash was functionalized with different silylating agents to produce silica with CH2 Cl (labelled as RHACCl), CH2 NH2 (labelled as RHAPrNH2) and CH2 SH (labelled as RHAPrSH) end groups via a novel one pot synthesis. Saccharine (Sac) and Melamine (Mela) were immobilized onto RHACCl to form RHAC-Sac and RHAPrMela. The functionalized CH2 SH group in RHAPrSH was oxidized to sulfonic acid, CH2 SO3H (labelled as RHAPrSO3H) with hydrogen peroxide at room temperature. The catalysts showed good textural and structural properties. RHAC-Sac, RHAPrMela, RHAPrSO3H, RHA Blank (as control) as well as homogenous Sac and homogenous Mela were used as catalysts in the esterification reaction. The catalytic activity was found to follow the sequence: RHAPrSO3H RHAPrMela homogenous Sac RHAC Sac homogenous Mela RHA Blank. The catalysts were easily regenerated and could be reused several times without loss of catalytic activity.