Thermoluminescence (TL) response of silica nanoparticles synthesized by the sol-gel method is presented here. Transmission electron microscopy (TEM) was used to find out the size and morphology of the pure silica nanoparticles. By using an appropriate amount of tetraethylorthosilicate, ethanol, deionized water and ammonia solution, silica samples were synthesized. To determine the best TL response of silica, samples were irradiated with 50Gy gamma rays. The effect of size dependency towards TL yield indicates that decreasing the particles’ size of silica, increases the TL yield.