Metal sulfides having a micro-porous structure are disclosed for use as sorbents for removal of mercury from flue gas. Systems are disclosed for making and using micro-porous particulates at least partially composed of alkaline earth metal and transition metal sulfides as sorbents. Calcium sulfide micro-porous powders derived from the high temperature reduction of calcium sulfate and calcium sulfite are disclosed to be reactive substrates for a group of sorbents for adsorption of mercury from the myriad of coal combustion flue gases produced by the utilities industry, as well as from natural gas and gaseous and liquid hydrocarbons. Controlled addition of one or more of polyvalent metal ions, chloride ions, polysulfide ions, and sulfur to the micro-porous calcium sulfide substrate produces the sorbent. The sorbents are useful for cost-effectively adsorbing elemental mercury and oxidized mercury species such as mercuric chloride from flue gases, including those containing acid gases (e.g., SO.sub.2, NO and NO.sub.2, and HCI), over a wide range of temperatures.