Creation of semiconductor metal oxide nanoparticles is one of the important topics to understand relationships between the microstructures and performance of their materials. In general, hydrothermal reactions are often used to produce structure-controllable highly-crystallized nanoparticles, where several factors, such as size and shape, can be precisely tuned at high temperatures. The purpose of this research is to design a new method of low-temperature production that enables the formation of 3D SnO₂ nanocrystals with an organic ligand as a structure directing agent. A low-temperature sol-gel process as low as 40°C for 7 days was applied for the synthesis of SnO₂. Also, this research was focused on the elucidation of the growth mechanism of such SnO₂ nanoparticles at a low temperature. Sn (II) precursors were hydrolyzed to produce the SnO₂ powder samples through freeze-drying process. A conversion of the Sn (II) species into SnO₂ was proved using X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). High-resolution TEM measurements clearly indicated the formation of SnO₂ nanoaggregates consisting of particles of around 5 nm in size. Even for the sample of 2days reaction, it turned out that SnO₂ was identified as the only tin species without any other Sn (II) intermediates. Brunauer-Emmett-Teller (BET) surface area of the obtained SnO₂ was also evaluated in order to understand the growth mechanism of the SnO₂ nanostructures. It was found that the oxalate organic ligand coexisting in the reaction mixture determined the scale of the specific surface area of SnO₂ nanoaggregates. Such ligand-assisted low temperature synthesis would provide a beneficial method to control both 3D microstructures and surface areas of SnO₂ nanoparticles.