Manganese speciation in exhaust particulates of automobiles using MMT-containing gasoline monochromator, 50% detuned, was used. Multiple scans varying from 4 sweeps for XANES and 8 sweeps for EXAFS were performed to yield optimal S/N ratios. All spectra were collected in the QEXAFS mode (Frahm, 1988). A manganese metal standard foil located in front of a reference ion chamber was measured simultaneously with each sample for in-situ energy calibration.