Rare earth vanadates have been studied extensively and they are of great interest as better hosts for luminescence materials. Eu3+-doped YVO4 is one of the most interesting phosphor materials due to its applications in field emission display and plasma display devices. In this research, Eu3+-doped YVO4 nanoparticles were prepared by two solution-based chemical methods. First method, Eu3+-doped YVO4 nanoparticles were prepared by a sol-gel method. Carboxylic acids such as citric acid, malic acid and tartaric acid were used as chelating agents. The effect of calcination temperatures (500 oC, 600 oC and 700 oC) on structure, crystallinity, size and morphology of the Eu3+-doped YVO4 nanoparticles were studied. Fourier transform infrared spectroscopy (FT-IR) spectra of the products showed the broadband absorption peak of VO43− and Y(Eu)–O stretching appeared in 750-950 cm-1 and 450-460 cm-1 regions, respectively. The products, characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), were tetragonal YVO4 nanoparticles with lattice parameters a = b = 7.0570 nm and c = 6.2562 nm. The crystallinity and particle sizes of the products increased with increasing calcination temperatures. However, all of the products are within nano-scale with diameters of about 30–60 nm therefore the products calcined at 700 oC were used for the transmission electron microscopy (TEM) and UV-Vis spectroscopy. It was found that the product treated with the malic acid had the smallest particle size but that treated with the tartaric acid had the greatest particle size. The band gap energies of the products treated with malic acid, citric acid and tartaric acid were determined as 5.65, 5.62 and 5.62 eV, respectively. Eu3+-doped YVO4 nanoparticles with controllable size were fabricated by a solvothermal method at 300oC for 3 hours employing methanol-water solution. The effect of the solution pH on size and morphology of the Eu3+-doped YVO4 particles was examined. SEM micrographs have revealed that the powders are composed of raspberry-like particles with a diameter of 250-450 nm that are comprised by the primary spherical particles in the range of 14-20 nm. The sizes of the primary particles decrease with the increase of pH. Post-annealing at 1000oC improved the luminescence intensity of the Eu3+-doped YVO4 red phosphor, whereas the raspberry-like shapes of the powders prepared in acidic solutions have retained. The powders prepared under basic conditions experienced considerable sintering. Moreover, GdVO4 nanoparticles have been prepared by the sol-gel method using tartaric acid as chelating agent followed by calcinations at 500o-700 oC for 3 h. The X-ray diffraction (XRD) patterns indicate that pure GdVO4 has a tetragonal structure and their lattice parameters are a = 7.1599 nm, c = 6.3242 nm. The increase in the crystallinity is by increasing the calcination temperatures. The fourier transform infrared spectroscopy (FT-IR) spectra show the broadband absorption peak of VO43−stretching in the 750-950 cm-1 region and weak absorbtion peak of Gd-O bond at 452 cm-1. The scanning electron microscopy (SEM) and the transmission electron microscopy (TEM) images show that the powders calcined at 500o-600oC compose of spherical nanoparticles with diameters of about 35-100 nm. But the average particle size of the powder calcined at 700oC quite aggregated to form macro-scale. The ultraviolet visible spectroscopy (UV-vis) spectra show the band gap energy that decrease as increasing the calcination temperatures. The effect of the molar ratios of total metal ions to tartaric acid on size and morphology of the GdVO4 nanoparticles was also studied.