In this work,- ErNbO4 samples were prepared using the sol-gel method,- through the citrate route,- and heat-treated at temperatures between 700 and 1600 °C. The structure was studied by X-ray diffraction and Raman spectroscopy. The crystallite size was estimated using the Rietveld refinement and the Sherrer's formula,- presenting values from 31.27 to 86.65 nm and from 40.96 to 78.23 nm,- respectively. The morphology was studied by scanning electron microscopy. The measurement of the complex permittivity was made using the small perturbation technique,- with a cavity operating in TE105 mode,- at resonant frequency of 2.7 GHz. The increase of the treatment temperature promoted the increase of the dielectric constant and the dielectric losses were still maintained with low values,- allowing their potential application in electric storage devices. The dielectric constant of ErNbO4 in a zero porosity sample case was estimated and compared with the experimental values. © 2020 Elsevier Ltd