This work has been developed with the objective to determine the effect of the increase in temperature of substrate on its refractive index and roughness of thin films of tantalum nitride (TaN). The thin films of TaN were deposited on (100) and (111) silicon wafers, by the technique of reactive magnetron sputtering with the direct current using a mixture of argon-nitrogen gases at substrate temperatures of 473 K, 573 K and 673 K, respectively. The Samples were characterized with an X-ray diffractometer (XRD), the Auger electron spectroscopy (AES) technique, a scanning electron microscope (SEM), a spectral ellipsometer (SE) and an atomic force microscope (AFM). The synthesized TaN thin films had a face-centered cubic (fcc) crystal structure, which did not change with increasing temperature, however; new directions of the crystallographic planes appear and the intensities of the diffraction peaks decreased. The samples were composed of tantalum (65 %), nitrogen (28 %), oxygen (5.3 %), carbon and argon. The refractive index decreased with increasing temperature for wavelengths between the visible and near-infrared range 4000-12 000 Å, while the roughness increased as the temperature increased, evidencing non-stable behaviour.