Abstract: Graphene oxide (GO) was synthesized by the reaction of graphite with sodium nitrate and the graphite/sodium nitrate mass ratio and the reaction time were varied in order to obtain the highest oxygen content. The GO was characterized by TEM, SEM, AFM, XRD, FT-IR, TGA, elemental analysis, and UV-vis and Raman spectroscopy. The effect of oxygen content on the physicochemical properties of GO was investigated. Results indicate that increasing the graphite to sodium nitrate ratio increases the oxygen content, BET surface area, pore volume and pore size but reduces the crystallite size of the GO samples. However, the oxygen content of GO is not directly related to the reaction time. Physicochemical properties such as d-spacing and defect density increase with increasing oxygen content while the thermal stability decreases. The physicochemical properties such as oxygen content, crystallinity, thermal stability and structure can be tailored by varying the graphite/sodium nitrate ratio and reaction time.