Determining of phenol and nitrophenols using solid-phase extraction on-line coupled to supercritical fluid chromatography (SFC) is studied. SFC quickly separated the compounds studied, in less than 6 min, and solid-phase extraction was used to decrease the limits of detection. C18, PLRP-S and a highly cross-linked styrene-divinylbenzene copolymer in a 10 x 3 mm I.D. laboratory-packed precolumn were tested comparatively as sorbents in the preconcentration step. Tetrabutylammonium bromide was used as ion-pair reagent in the extraction process to increase breakthrough volumes, mainly for phenol. Performance of the method was checked with tap and river waters.