Proposed herein is a method based on the Levenberg-Marquadt technique to retrieve an approximated average phonon dispersion curve from Raman spectra of nano-sized crystals. To this end we deal with a modified form of the well-known phonon confinement model in which the intrinsic linewidth Gamma(0) is replaced by an effective linewidth Gamma. An application to experimental results obtained on TiO2 nano-crystals is presented as a test of the method. (C) 2008 Elsevier B.V. All rights reserved.