An analytical method for separation and quantification of five acridine thio derivatives by capillary liquid chromatography has been developed. A capillary column, 320 mm I.D., filled with the Nucleosil 100-5 C 18 stationary phase, particle size 5 mm, was used. The mobile-phase composition was optimized in order to obtain a reasonable separation of the main component of each reaction mixture from impurities from the synthesis and a good quantification. It was shown that all the derivatives studied were well separated in binary mobile phases, acetonitrile/water or acetonitrile/0.2 mol.dm^-3 acetate buffer of pH 3.5, with high acetonitrile contents (90 %). Calibration curves for all the derivatives were measured at wavelengths of 214 and 230 nm in the mobile phase composed of acetonitrile/0.2 mol.dm^-3 acetate buffer of pH 3.5 (90:10, v/v). The linear dynamic ranges of the calibration curves were between 1.0×10^-3 and 1.0×10^-6 mol.dm^-3 and the detection limits for the compounds were in the µmol.dm^-3 range.