Oxidative sorbents are provided for adsorbing elemental or oxidized mercury from mercury-containing fluids such as flue gas from a coal-burning power utility or the like at a temperature range of about 50 to 350° C. The method of preparing and using the oxidative sorbents is also provided. The oxidative sorbent compositions include one or more silicates capable of cation exchange with a plurality of active metal cations and their counter anions. The silicates may include those selected from clays such as montmorillonite, laumonite, bentonite, Mica, vermiculite and kaolinite, and from silica gels, natural and synthetic molecular sieves, zeolites, and ashes from stoker- and pulverized coal-fired boilers. The one or more oxidative metal halides and / or sulfates may be selected from the group consisting of CuCl, CuBr, CuCl2, CuBr2, CuSO4, FeCl2, FeCl3, FeSO4, Fe2(SO4)3, ZnCl2, ZnBr2, NiCl2, and NiSO4. The oxidative sorbents may also include activated carbon.