The burning of simulated waste lubricating oils containing lead or barium, and the fate of these metals in the presence of sorbents during combustion were investigated in a 13 kW horizontal combustor. An organometallic, lead (II) ethylhexanoate or barium naphthenate, mixed with heptane was burned with air yielding between 15 and 300 ppm, of the metal in the gases. Sorbent (kaolinite or hydrated lime) was introduced upstream of the reaction zone. Samples of lead or barium collected without sorbent injection showed the metals＇ particle size distributions in the submicron range. A computer code, MAEROS2, was adapted to predict lead oxide particle size distribution for similar combustor conditions and compared with experimental results of Linak et al. (1995). The sorbents were effective in scavenging lead. With kaolinite sorbent, lead concentrations were inversely proportional to particle diameter. Even with sorbent, the barium was found predominantly in the submicron size range suggesting little adsorption.