Results of the application of the attenuated total reflection (ATR) technique in the UV-Vis wavelength range to process liquids from pulp industry are reported. The experimental set-up consists of a Xenon light source, an ATR probe, a monochromator, and a CCD detector. The technique is applied in the laboratory environment both to solutions from the pulp process and synthetic model solutions. Quantitative results are obtained when the method is used to determine lignin concentrations. However, the technique suffers from drift and a recovery problem causing reproducibility problems when applied to liquids from pulp industry. Possible reasons for the observed behavior are studied. Reproducible results are obtained by including a washing stage in the measuring sequence.