TiO2 is an inorganic oxide with high efficiency in terms of photocatalytic activity and promising thermoelectric properties with applications such as water splitting and bacterial growth inhibition. Owing to the unique MagnÃ©li phase which enhances the electrical conductivity, titanium oxides with oxygen defects have attracted attention for thermoelectrics. In this dissertation, the synthesis of nitrogen doped TiO2 nanoparticles and TiC@TiO2 nanoparticles by modified sol-gel method were realised. To the best of our knowledge, this is the first example of a low temperature anatase-to-rutile phase transformation by sol-gel methodology, elicited by nitrogen doping of the TiO2. The powder XRD characterisation reflected that with the increase of the nitrogen doping amount, the anatase phase of TiO2 transformed to the rutile phase, and the change of the phase composition was further confirmed by Rietveld Refinement. The mixed-phase TiO2 was also characterised by Raman spectroscopy. The SEM results showed that the particle size of the N-doped TiO2 is in the range of nanometers. EDX spectroscopy was used to probe dopant incorporation which suggested substitution of N for O in the material. These results proved the feasibility of mixed-phase TiO2 nanoparticles through the modified sol-gel method at low temperatures. These mixed-phase TiO2 nanoparticles are expected to be useful for photocatalytic and thermoelectric applications with tunable properties.