The objective of the present work is to verify the reduction of CrO3 in concentrated hydrochloric acid, using 51Cr as a tracer. For the study, 51CrO3 was added to 37% HCl and maintained under agitation at 20 °C for specified time periods. Aliquots were diluted to approximately pH 2 and analyzed by open column cation and anion chromatography, either immediately or after storage for specified time periods. The separations, which were made by stepwise elution using HClO4 and Ca(ClO4)2 solutions as eluents with fraction collection, followed by counting with a NaI(TI) detector and a single channel analyzer, permitted construction of elution profiles whose peaks were identified by comparison with authentic samples. The results show that CrO3 is reduced to Cr(III) in 37% HCl and that the initial identifiable product is [CrCl3(H2O)3], a product which undergoes slow aquation at pH 2 to [Cr(H2O)4Cl2]+, [Cr(H2O)5Cl]2+ and [Cr(H2O)6]3+.8911-12845847Weeks, M.E., Leicester, H.M., (1968) Discovery of the Elements. 7 th ed., , American Chemical Society, EastonFeigl, F., Spot reaction experiments (1943) J. Chem. Educ., 20, p. 240Krauss, H.L., Leder, M., Münster, G., Zur chemie der chrom(V)-verbindungen (1963) Chem. Ber., 96, p. 3008Bobtelsky, M., Glasner, A., The oxidation of hydrobromic acid by chromic acid in the presence of manganous sulphate (1948) J. Chem. Soc., p. 1376Ho, W.-H., The kinetics of the reaction of chromium(VI) and nitrous acid (1979) Proc. Natl. Sci. Counc. ROC, 4, p. 1Archundia, C., Collins, C.H., Collins, K.E., Speciation of the reaction products of 51Cr/VI/with formic acid (1990) J. Radioanal. Nucl. Chem. Lett., 146, p. 49Khan, Z., Hashmi, A.A., Din, K., Reduction of chromium(VI) by phosphonic acid (1998) Transition Met. Chem., 23, p. 147Smith, G.F., Mixed perchloricsulphuric acids. I. Simultaneous oxidizing and reducing properties of hot concentrated perchloric acid (1934) Ind. Eng. Chem. Anal. Ed., 6, p. 229Archundia, C., Bonato, P.S., Lugo Rivera, J.F., Mascioli, L.C., Collins, C.H., Collins, K.E., Reduction of low concentration Cr(VI) in acid solutions (1993) Sci. Total Environ., 130-131, p. 231Archundia, C., Lugo Rivera, J.F., Collins, K.E., Collins, C.H., Speciation of the products from acid reduction of Cr(VI) (1995) J. Radioanal. Nucl. Chem. Art., 195, p. 363Pezzin, S.H., Archundia, C., Collins, C.H., Collins, K.E., Radiometric and spectrophotometric studies of the behavior of chromium(VI) oxide in concentrated perchloric acid (1997) Radiochim. Acta, 77, p. 91Pezzin, S.H., Collins, C.H., Archundia, C., Collins, K.E., Speciation of the products resulted from the reaction of 51Cr(VI) with concentrated perchloric and trifluoromethanesulfonic acids (1998) J. Radioanal. Nucl. Chem., 236, p. 209Pezzin, S.H., Archundia, C., Collins, K.E., Collins, C.H., Product speciation and aquation after the reaction of 51Cr(VI) with concentrated HCl or H2SO4 (2000) Czech. J. Phys., 50, p. 315Pezzin, S.H., Collins, C.H., Collins, K.E., (2000) Estudo da reação entre 51CrO3 e ácido nitrico concentrado por métodos radiocromatográficos, E01, p. 61. , V Encontro Nacional de Aplicações Nucleares, Rio de Janeiro, Brazil, outubro de 2000, AnaisPavel, J., Kliment, J., Stoerk, S., Suter, O., Preservation of traces of chromium(VI) in water and waste water samples (1985) Fresenius Z. Anal. Chem., 321, p. 587Stollenwerk, K.G., Grove, D.B., Reduction of hexavalent chromium in water samples acidified for preservation (1985) J. Environ. Qual., 14, p. 386Gil, M., Escolar, D., Iza, N., Montero, J.L., Accuracy and linearity in UV spectrophotometry with a liquid absorbance standard (1986) Appl. Spectrosc., 40, p. 1156Collins, C.H., Collins, K.E., Ackerhalt, R.E., Cation exchange separation of 51Cr-labelled species in aqueous Cr(VI)-Cr(III) solution (1971) J. Radioanal. Chem., 8, p. 263De Andrade, J.C., Collins, K.E., Tomeiras de PTFE para uso geral em laboratório (1981) Quím. Nova, 4, p. 89Collins, C.H., Pezzin, S.H., Lugo Rivera, J.F., Bonato, P.S., Windmöller, C., Archundia, C., Collins, K.E., Liquid chromatographic separation of aqueous species of Cr(VI) and Cr(III) (1997) J. Chromatogr. A, 789, p. 469Collins, K.E., Bonato, P.S., Archundia, C., De Queiroz, M.E.L.R., Collins, C.H., Column chromatographic separation of chromium for Cr(VI) and several species of Cr(III) (1988) Chromatographia, 26, p. 160Autenrieth, W., Ueber einige chromsaure und dichromsaure salze (1902) Ber. Deutsch. Chem. Ges., 35, p. 2057(1985) Annual Book of ASTM Standards, Section 3, Vol.03.05, "Chemical Analysis of Metals and Metal-Bearing Ores", , American Society for Testing and Materials, PhiladelphiaOttaway, J.M., Fell, G.S., Determination of chromium in biological materials (1986) Pure Appl. Chem., 58, p. 1707