The solubility of Cr2O3(s) in (1 and 6) mol kg(-1) sodium hydroxide solutions has been investigated at 25 degrees C. Even after 75 days of solid/solution contact the apparent solubility continued to increase slowly. Analysis of the solution phase by UV-vis spectrophotometry revealed that all of the dissolved chromium was present as Cr(VI), in the form of CrO42-(aq); no Cr(III) could be detected. Consistent with this finding, Cr(III) dissolved in 6 mol kg(-1) NaOH was found to be oxidized to CrO42-(aq) over of period of days. No significant changes to the solid phase, Cr2O3(cr), were found, either by X-ray diffraction or by X-ray photoelectron spectroscopy, as a result of its contact with NaOH(aq). Both CrO42- and Cr(III) were found to be unreactive toward a range of organic and inorganic compounds in 6 mol NaOH over many days at ambient temperatures. However, CrO42- catalyzed the decomposition of L-ascorbate, and was rapidly reduced by elemental Zn to Cr(III) in NaOH(aq).