Terbium-doped gadolinium oxysulfide (Gd<sub>2</sub>O<sub>2</sub>S:Tb) nanoparticles were synthesized by hydrothermal precipitation of urea. On the reaction, were analyzed variables as the temperature of solutions, the reaction time and the stirring velocities as main factors in the crystal growth. WAXD TEM and FTIR analysis were used to characterize the Crystallographic phase, morphology and chemical vibrations of the materials. Moreover, the photoluminescent properties were evaluated as response at the UV light, obtaining the main emission at 544 nm produced by <sup>5</sup>D<sub>4</sub> → <sup>7</sup>F<sub>5</sub> transition of the Tb<sup>3+</sup> ions. Besides, we found that the host lattice and doped-ions concentration is essential to obtain a strong visible photoluminescence evaluated experimentally.