This article presents the results of a study of calcium sorbent sulfation in synthetic flue gas atmospheres, both dry as well as steam-containing. The tests were carried out under laboratory conditions for synthetic flue gases containing 2,000 ppm, 3,000 ppm, and 4,000 ppm of SO₂, 5% oxygen, and 30% or 50% of CO₂. Some selected tests were also performed with the addition of up to 30% vol. of steam to the flue gas. The studies were carried out at 750^oC and 850^oC for a sorbent particle size of <50 microns and purity (CaO content) of over 98%. The processes of sorbent sulfation at higher concentrations of CO₂ and SO₂ were different from ‘classical’ sulfur capture in air since sorbent calcinations were limited and direct reaction between limestone and gaseous sulfur dioxide occurred. The study results also indicated that the presence of water steam in the flue gas positively affects the process conditions, thus contributing to the amount of sulfur dioxide absorbed by sorbent samples. However, too high a content of H₂O in the gas (over 15% vol.) was not desirable since it decreased the overall coal sulfation process.