Carbon-doped titanium dioxide nanoparticles were prepared by ultrasonic spray pyrolysis technique using titanium tetra-ethoxide as a precursor and glucose as a dopant. The as-synthesized nanoparticles were then characterized using high resolution transmission electron microscopy for the structural properties and temperature dependence Raman spectroscopy for the optical properties. High resolution transmission electron microscopy analysis shows that the ultrasonic synthesized carbon-doped titanium dioxide nanoparticles have an interplanar d-spacing of 0.352 nm, a value close to 0.374 nm of the pure undoped anatase titanium dioxide (bulk). The fast Fourier transform (FFT) of the selected electron diffraction images, of the selected areas, display the fact that only the main diffraction (reflection) plane of Miller indices (101) in titanium dioxide is responsible for diffraction pattern. Raman spectroscopy confirms the titanium dioxide polymorph to be anatase with the intense phonon frequency at 153 cm(-1) blue-shifted from 141 cm(-1) due to both carbon doping and particle size decrease. The temperature dependence analysis of the spectra shows an initial linear dependence of the Raman shift for the E(g(1)) mode at 152.7 cm(-1) with increase in temperature up to a critical temperature 450 degrees C, after which we observe a decrease with increase in temperature. The other Raman modes [B(1g) and E(g(3))] exhibit a different temperature dependence in that the B(1g) displays a somewhat sinusoidal behavior and the E(g(3)) mode shows a linear decrease of Raman shift with an increase in temperature. Temperature dependence analysis of peak width for the E(g(1)) indicates the peak width of the as prepared nanoparticle to be 20 cm(-1) which is far much larger than that for single crystal of 7 cm(-1) at room temperature.