The paper presents dealswith the effect of poly vinyl alcohol (PVA) amount as gel making agent of sol-gel combustion method on the morphology and the particles sizes of chromium oxide nanostructures (CONS). Chromium nitrate is dissolved in 1:1 water ethanol mixed solvent. Some different amounts are dissolved in the chromium nitrate solution under controlled temperature to make a sol. The solvent of the sol is evaporated under controlled temperature to obtain a high viscous material which called gel. The suitable pyrrolysis temperature of the gel is found by TGA/DTA analysis. The homogenous gel is slowly pyrrolized under 500 ºC by an electrical furnace to obtain a CONS sample. Five different samples are synthesized by using different amounts of PVA. The morphology, particles sizes and the composition of the CONS is characterized by SEM, TEM, XRDandDLS.