Aerosol property measurements including primary particle, radius of gyration, and number of primary particles per agglomerate have been performed for soot collected thermophoretically from the soot annulus at selected heights of laminar ethene/air, methane/air, and methane/oxygen diffusion flames and analyzed using a digital image processing technique. The fractal dimension D, and prefactor term k(f) calculated front these measurements were used to determine whether there exists it universality of these properties for inflame soot or any correspondence with previous Measurements performed in the overfire region of large turbulent flames. The fractal dimension measured in this study ranged from 1.65 to 1.75, in agreement with previous measurements obtained for both in-flame and overtire soot, Measurable variations in the prefactor values, which ranged from 6,75 for the methane/air diffusion flame, to 8.47 for the ethlene/air diffusion flame. were observed. An error analysis performed for these results indicated that there is up to 6 percent and 22 percent uncertainty in the fractal dimension and prefactor values, respectively.