X-ray absorption fine structure (XAFS) spectroscopy data were obtained from particulate samples produced by the combustion of residual fuel oil in a 732-kW fire-tube boiler at EPA's National Risk Management Research Laboratory in North Carolina. Residual oil flyash (ROFA) from four oils of varying sulfur content were aerodynamically separated into < and > 2.5 micrometer fractions using a cyclone. Spectra were obtained at the S, V, Ni, Fe, Zn, and As K-shell photoelectric x-ray absorption threshold energy (K-edges). Preliminary analyses have been carried out on the S, V, and Ni x-ray absorption near-edge structure (XANES) spectra. Deconvolution of the S XANES reveales that the dominant molecular forms of sulfur observed are sulfate and thiophenic sulfur. Sulfate was greater in the < 2.5 micrometer samples than in the > 2.5 micrometer samples, possibly reflecting the different mechanisms influencing the formation of large and small particles. Inorganic sulfides and elemental sulfur were present in lower percentages. The Ni XANES spectra from all the ROFA PM samples agree fairly well with that of NiSO4, while the V spectra most closely resemble the spectrum of vanadyl sulfate.