Abstract: This invention concerns highly reactive reagents and compositions for purifying exhaust gases and flue gases and for purifying wastewater as well as the processes for producing same and use thereof.The reagents and compositions are mixtures of calcium hydroxide with additives, especially clays, powdered bricks, carbon products such as coal dust and flue ash and optionally water glass which are already porous due to their special production and have a high specific surface area of up to about 200 m.sup.2 /g.Using these sorbents, hydrocarbons and halogenated hydrocarbons, dioxins and furans in addition to heavy metals can be removed from exhaust gases and wastewater. Other advantages include the easy setup of the resulting products and their great safety for dumping.