Relatively high indoor CO2 concentration (>1,000 ppm) has a negative impact on human health. In this work, indoor CO2 adsorbent was developed by impregnating KOH or K2CO3 on commercial activated carbon, named as KOH/AC and K2CO3/AC. Commercial activated carbon (AC) showed relatively high BET surface area (929 m2/g) whereas KOH/AC and K2CO3/AC presented lower BET surface area of 13.6 m2/g and 289 m2/g. Two experimental methods of TGA (2,000 ppmCO2, weight basis) and chamber test (initial concentration: 2,000 ppmCO2, CO2 IR analyzer) were used to investigate the adsorption capacity. KOH/AC and K2CO3/AC exhibited similar adsorption capacities (145~150 mgCO2/g), higher than K2CO3/Al+Si supports adsorbent (84.1 mgCO2/gsample). Similarly, chamber test also showed similar trend. Both KOH/AC and K2CO3/AC represented higher adsorption capacities (KOH/AC: 93.5 mgCO2/g K2CO3/AC: 94.5 mgCO2/gsample) K2CO3/Al+Si supports. This is due to the KOH or K2CO3 impregnation increased alkaline active sites (chemical adsorption), which is beneficial for CO2 adsorption. In addition, the regeneration test results showed both K-based adsorbents pose a good regeneration and reusability. Finally, the current study suggested that both KOH/AC and K2CO3/AC have a great potential to be used as CO2 adsorbent for indoor CO2 adsorption.