The husk of rice contains high levels of silica when calcined. This work was carried out to study the nature of the organic components where the silicon complexes are nucleated and the best conditions for the synthesis of SiO2. The husk of rice and silica were analized by SEM, DRX, FTIR, TGA. The husk was treated with HCl to eliminate impurities as Fe, Na, K, etc. The results show that silica nucleates in the external part of the husk, composite of cellulose. SiO 2 is amorphous, with a high specific surface (~2772 m 2 /g), arbitrary morphology and nanometric size