Highly microporous nitrogen-enriched activated carbons were in situ synthesized by using K2C2O4 H2O as an activating agent and Procambarus clarkii shells as a carbon and nitrogen (N) source. The obtained samples exhibit good CO, adsorption performance at 1 bar ranging from 4.99 to 6.48 mmol/g at 0 C, and from 2.55 to 4.51 mmol/g at 25 degrees C, respectively. In particular, a high CO, adsorption capacity of 4.51 mmol/g at 25 degrees C was achieved for the sample prepared by using the K2C204.H20/precursor mass ratio of 3 and activated at 700 degrees C. The high CO2 uptake was achieved because of a unique microporous structure and high N content. Furthermore, the CO2/N-2 selectivity and CO, adsorption heat of this carbon are as high as 52 and 33 kJ/mol, respectively. In addition, this carbon exhibits excellent reusable stability and a high dynamic CO, capture capacity of 0.79 mmol/g under conditions mimicking aflue gas environment. The aforementioned advantages demonstrate that the obtained N-enriched activated carbon can be a potential alternative for capturing CO2.