The simultaneous adsorption of SO2, NO, and CO2 on K2CO3-modified -alumina under different operating conditions was studied in a fixed-bed reactor. The experimental results showed that the influence of a temperature increase on the simultaneous adsorption of the three gases was complex and different from the effects seen when both chemical adsorption and competitive adsorption existed. An increase in O2 concentration and small amounts of water could enhance the adsorption of SO2 and NO while the adsorption of CO2 was not influenced. The breakthrough curves of the simultaneous adsorption experiments suggested that the investigated adsorbent may be a good candidate for the simultaneous adsorption of SO2, NO, and part of the CO2 while the adsorption capacity for CO2 still needs to be enhanced.