Potassium carbonate (K2CO3) is recognized as a potential candidate for CO2 capture by flue gas under moist conditions because of its high sorption capacity and low cost. However, undesirable effects and characteristics that are associated with the desorption process, such as the slow reaction rate and the high regeneration temperature, lead to high energy costs and thus hinder its application. To improve the CO2 capture properties of K2CO3 under moist conditions, we investigated in this study the reaction rate and the regeneration temperature of a K2CO3 -carbon composite (KC-CC), which was prepared from terephthalic acid and KOH. The successful synthesis of KC-CC was confirmed by the X-ray diffraction and Raman spectrometry results, while the CO2 capture characteristics of KC-CC under moist conditions were examined by thermogravimetric analysis. The CO2 capture experiment was repeated twice. The CO2 capture by KC-CC was faster than that by bulk K2CO3, while after the CO2 capture, the regeneration proceeded at lower temperatures compared to bulk KHCO3. Moreover, after a 10-cycle repetition of the CO2 capture experiment, KC-CC exhibited a stable performance. Thus, compared to bulk K2CO3, KC-CC could efficiently capture CO2 at an increased reaction rate and a lower regeneration temperature. This may be due to the nanostructural properties of KC-CC, which were also indicated by the results of XRD analysis.