Spherical carbonaceous adsorbents (CS.) with micro-porosity developed for CO2 capture were prepared by a simple hydrothermal carbonization of carboxymethylcellulose (CMC) in the presence of urea, and activated in a high temperature N-2 atmosphere. The effects of specific surface area, pore structure, and N content on the CO2 adsorption capacity were systematically investigated. Urea was found to react with surface carbonyl groups and other intermediate products generated by CMC hydrothermal carbonization, which produced highly spherical morphologies that also exhibited some ordered lattice structures. The particle size of N-doped CSn was larger than that of particles prepared without urea. Nitrogen was mainly present in pyridine (N-6), pyrrolic/pyridone (N-5) and quaternary (N-OJ forms. The high CO2 capture capacity was produced by a combination of N-doping and developing micro-pore structures. At an adsorption pressure of 1 bar, the capacity was dominated by the micro-porosity. However, during initial, lower pressures the N content dominated the CO2 adsorption capacity. (C) 2016 Elsevier B.V. All rights reserved.