Sorghum vulgare seed heads (SVSH) as agricultural waste have now become a low cost raw material for nanosilica preparation, because it contains silica. The objective of the present work is to establish a procedure to prepare pure nanosilica from SVSH. In first step the SVSH was calcinated at 700 degrees C to reduce the organic contents. After calcination, the ash was posted to three kinds of chemical treatments that are i) acid mixture, ii) 3% hydrochloric acid and iii) sodium hydroxide. Then the prepared nanosilica was characterized by High Resolution Scanning Electron Microscopy (HR-SEM), Energy-Dispersive X-ray Spectroscopy (EDX), Powder X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The HR-SEM results show the nanostructure of silica. XRD pattern of acid leached SVSH ash formed crystalline nanosilica, whereas nanosilica obtained from precipitation method was amorphous in nature. The FT-IR spectrum adds evidence indicating the presence of silica. (C) 2012 Elsevier B.V. All rights reserved.