The feasibility of implementing a Sn(II) oxy-hydroxide (Sn 6 O 4 (OH) 4 ) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr- K -edge. The analysis of the Cr- K -edge XANES and EXAFS spectra verified the effective use of Sn 6 O 4 (OH) 4 for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn 6 O 4 (OH) 4 can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH) 3 precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO 2 , which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ( 2 C) and monodentate ( 1 V) geometries, at the expense of the present bidentate mononuclear ( 2 E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn 6 O 4 (OH) 4 in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the 2 C and 1 V configurations, which enhances the safe disposal of spent adsorbents. [ABSTRACT FROM AUTHOR]