Highly porous carbons have been prepared by the chemical activation of two mesoporous carbons obtained by using hexagonal- (SBA-15) and cubic (KIT-6)-ordered mesostructured silica as hard templates. These materials were investigated as sorbents for CO 2 capture. The activation process was carried out with KOH at different temperatures in the 600–800°C range. Textural characterization of these activated carbons shows that they have a dual porosity made up of mesopores derived from the templated carbons and micropores generated during the chemical activation step. As a result of the activation process, there is an increase in the surface area and pore volume from 1020m 2 g −1 and 0.91cm 3 g −1 for the CMK-8 carbon to a maximum of 2660m 2 g −1 and 1.38cm 3 g −1 for a sample activated at 800°C (KOH/CMK-8 mass ratio of 4). Irrespective of the type of templated carbon used as precursor or the operational conditions used for the synthesis, the activated samples exhibit similar CO 2 uptake capacities, of around 3.2mmolCO 2 g −1 at 25°C. The CO 2 capture capacity seems to depend on the presence of narrow micropores (<1nm) rather than on the surface area or pore volume of activated carbons. Furthermore, it was found that these porous carbons exhibit a high CO 2 adsorption rate, a good selectivity for CO 2 –N 2 separation and they can be easily regenerated.