Zn 2SnO 4 nanoparticles with a band gap of 2.96–3.36 eV were synthesized via a simple hydrothermal method using Na 2CO 3 as a new mineralizer. The effects of the concentration of Na 2CO 3 on the formation, morphology and optical properties of the Zn 2SnO 4 nanoparticles are discussed. Also, the reaction parameters, such as the reaction temperature and reaction time, were optimized. The as-synthesized Zn 2SnO 4 nanoparticles exhibit no impurity phases such as SnO 2 and ZnO throughout the entire process, as confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. Also, the formation of impurity free Zn 2SnO 4 nanoparticles in the presence of Na 2CO 3 is explained by a unique hydrothermal reaction sequence. The average particle size of the highly crystalline Zn 2SnO 4 nanoparticles was controllable by adjusting the mineralizer concentration, which enabled the facile tuning of the bandgap. From the photoluminescence (PL) study, two emission bands could be found after peak analysis, which are probably due to the presence of oxygen or cation vacancies generated during the hydrothermal process. These bands were shifted to lower frequencies as the concentration of the Na 2CO 3 mineralizer increased.