A commercial Fourier transform infrared (FTIR) spectrometer, modified for automated analysis of particulate-associated sulfate, was used to obtain transmission spectra of samples of particulate matter collected from the ambient air onto Teflon filters. An evaluation of the instrumentation was undertaken to determine its applicability for measuring sulfate and the correlation of results with those of ion chromatography and x-ray fluorescence. Particle samples from six geographical areas were analyzed in the study. Results from different filter sets, using individual filter blanks, show values of the coefficient of determination of 0.90 or higher for any two techniques with one notable exception. The exception is due to displacement of sulfate absorption from the wavelength interval used for analysis, and apparently indicates the effect of co-collected compounds in chemically shifting the spectra. The detection limit is 1.2 microgram/sq cm which corresponds to 0.4 microgram/cu m sampled over 24 hours at 13.3 L/min for ammonium sulfate.