Leachate generation is one of the main pollutants associated with municipal solid waste (MSW). Leachate is a liquid that has seeped through solid waste in a landfill and extracted dissolved or suspended materials in the process, and usually contains a complex variety of materials and organic compounds. Dedicated treatment facilities are required before leachate can be discharged to the environment. Researchers worldwide are still searching for a total solution to solve leachate problem. In this chapter, different chemical treatment methods for leachate including coagulation–flocculation, Fenton and Electro-Fenton oxidation, persulfate oxidation, ozonation, and advanced oxidation processes are reviewed and discussed. Nevertheless, the efficiency of each process was also evaluated. It can be concluded that the performance of these processes is mainly attributed to leachate type and initial organic concentrations whereas treatment performance weakens reported at older age and higher initial concentrations of leachate.