[en] This work deals with the characterization of soot particles present in the plumes of highly ventilated turbulent diffusion flames. These fuels have been studied: acetylene, toluene and Poly-Methyl-Methacrylate. The size distribution of soot particles was measured on line after dilution, with a discussion about the response of the metrological devices to fractal aggregates. The fractal dimension and the pre-factor have been determined from electronic microscopy micrographs analysis. The effective density of the soot aggregates has ben also determined by a serial analysis of their electrical mobility and aerodynamic diameters. Then the refractive index of soot particles has been computed at two wavelengths (632 and 1064 nm) by an inversion method based on previous measurements and on measurements of extinction and vertical-vertical scattering coefficients. Results obtained from the three fuels appeared to be consistent with each other and mean values of refractive indices have been established (m = 1.56-0.61.i at 632 nm and m = 1.71-0.86.i at 1064). (author)