Extracellular synthesis of silica particles was carried out by Fusarium oxysporum mycelia using rice husk ash (RHA) as raw material. RHA before and after bioprocessing was analyzed by SEM and specific surface area. Dissolved silica was quantified using colorimetry. Incubation of rice husk ash with F. Oxysporum at 28°C and pH 6.8 indicated that 80% silica was dissolved and micrographs of RHA before and after reaction with fungi showed that the morphology of silica particles changed and the average size decreased (~600 to ~5 µm). Moreover, specific volume pore of particles was reduced from 0.026 to 0.013 cm 3 /g and surface area increased from 115 to 125 m 2 /g. Dissolved silica corresponds to 177 m 2 /g. It is concluded that synthesis of oxide materials using fungal biotransformation is a viable process to obtain added value products from agro-industrial waste materials.