The decolorization of a cationic dye,Cationic Yellow X-5GL,was carried out using birnessite-type manganese oxides prepared by the sol-gel method.On the basis of investigating the influences of factors, such as initial pH,the dose of birnessite-type manganese oxides,the study further discussed the influence of Mg2+,Ca2+,and heavy metal ions(Pb2+,Cd2+,Hg2+).The results showed that birnessite-type manganese oxides have well decolorization effect on Cationic Yellow X-5GL.The decolorization ratio can reach to 98% in five minute when pH was 2.5 and the dose of manganese oxides was 5mg.The metal ions above had no obvious effect on decolorization of dye.The decomposition date at pH 2.5 nearly followed first-order kinetics and the reaction rate constant is 0.2069min-1.