Corn cob considers the agricultural waste in Iraq. High purity SiO2NPs were extracted from corn cob by enhanced precipitation and developed leaching processes. In this study, pre-treatment with 3N HCl has achieved then calcination of the corn cob at 700°C, then follows with the leaching process with (2, 2.5, 3)N NaOH. The characterizations of the prepared SiO2NPs were analyzed with atomic force microscopy (AFM), and X-ray fluorescence (XRF). The results were found that the prepared SiO2NPs have an amorphous structure with a high purity of 97.13 %. Also, the AFM results indicated that the average diameter of the SiO2NPs was 85 nm. It was noted that the leaching processes and pretreatment methods determine the structure, particle size, and quality of the synthesized SiO2NPs.