The invention relates a process for preparing a microporous carbon material comprising the following steps: i) providing a cross-linked polymer obtainable by reacting either A1) a maltodextrin deriving from starch comprising amylose in the range from 25 to 50% expressed as dry weight relative to the dry weight of the starch or A2) a cyclodextrin with an organic aromatic dianhydride in a mass ratio of either maltodextrin or cyclodextrin with respect to the organic aromatic dianhydride in the range of 1:0.50 to 1:2, ii) pyrolyzing at a range from 700 to 900° C. with a heating ramp in the range from 5° C./min to 30° C./min in a inert gas flux; and iii) cooling the obtained residue. The microporous carbon material obtainable by the process of the invention consists of micropores having pore size distribution in the range from about 6 to about 16 Å and is used as absorber for liquids and gases.