In this work granular activated carbon has been chosen as an absorbent in order to investigate the Cr(VI) reduced by adsorption experiments. Several batch chromium-sorption experiments were carried out using 0.25g of granular activated carbon in 50mL aqueous solution containing approximately 70 and 140mgL-1 of Cr(VI) and Cr(III), respectively. Cr-KΒ fluorescence spectra of Cr adsorbed in a carbon matrix and Cr reference materials were measured using a high-resolution Johann-type spectrometer. Based on evidence from the Cr-Kb satellite lines, the Cr(VI) reduction process has actually happened during metal adsorption by the activated carbon. © 2010 Elsevier Ltd.