The Laser-Induced Incandescence (LII) technique is widely used for the study of soot production in ames. More recently, it has also drawn attention also for the characterization of metal-oxide ame synthesis. To retrieve the particle volume fraction from the LII signal, information on the eective particle temperature and the absorption function E(m) depending on the wavelength are needed. In this study, a new approach is proposed to determine these parameters from LII measurements at a given laser uence by accounting for the spectral shape of E(m) obtained from the estimated eective particle temperature. The feasibility of the method is rst demonstrated on a carbon black nanoparticle aerosol in a non-reactive cold environment. A good agreement with the literature data for E(m) is found. The developed approach is then applied to TiO2 nanoparticles produced by ame synthesis. The obtained spectral response of E(m) is in line with the literature results for TiO2. The proposed approach represents an essential step towards in-situ estimation of particle volume fraction from the LII signal, which can be a valuable tool for further characterization of metal-oxide ame synthesis.