In this study, an attempt has been made to comprehensively investigate the effect of adding 5 wt% titanium on the microstructural characteristics, mechanical and physical properties of titanium nitride-based ceramics. The sintering of TiN-5wt%Ti ceramics was carried out using the spark plasma sintering (SPS) process in a vacuum atmosphere, under a pressure of 50 MPa, at a temperature of 1900 °C for 7 minutes. The results showed that the lack of sufficient wettability between the titanium additive particles and the titanium nitride matrix phase and the trapping of gases resulting from possible reactions between the particles and residual oxygen during the sintering process were the reasons for the relative density of 92.5%. The formation of the titanium oxide phase during sintering was confirmed by the reactions of titanium with titanium nitride and residual oxygen using the results of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and thermodynamic evaluations. According to the laboratory results of nanoindentation test, the maximum hardness and Young's modulus were obtained at loading rates up to 0.8 mN/s. In addition, pop-in events were observed in the nanoindentation test curves due to the formation of microcracks and dislocation nucleation in the indentation areas. Also, finite element simulation of the nanoindentation test was performed using Abaqus software at the same experimental loading rates, i.e. 0.2, 0.4 and 0.8 mN/s, and a significant agreement was obtained between the laboratory findings and the simulation results.