Three 1,fC-!abeled fuels were burned as premixed flames: (a) 72 percent methanol in toluene; (b) 62 percent acetone in toluene; (c) 54 percent cyclohexane in toluene. These compositions correspond to 1:1 cofuel carbon:toluene carbon ratios. Soot, sampled from the yellow flame zone and collected on a glass-fiber filter, was assayed for 1,(C-activity. Results were analysed in terms of R, the relative probability of toluene carbon xofuel carbon conversion. R values of 2 and 50 were determined for cyclohexane and methanol respectively. Studies were carried out at 4:1 Na:02 composition and fuel:oxygen equivalence ratios of 1.6, 1.8 and 2.0. Fuel:oxygen equivalence ratio had minor impact on relative fuel-to-soot conversion.