The method of on-line supercritical fluid extraction/Fourier transform infrared spectrometry (SFE/FT-IR) has been applied to the analysis of fiber finishes on fiber/textile matrices. Three different fiber polymer types were examined, each requiring a different finish. Finishes ranged from a single-component poly(dimethylsiloxane) oil to more complex multicomponent finishes that included various surfactants, fatty acid esters and soaps, antioxidants, and oils. The three fiber types tested were polyurethane, polyamide, and aramid