An adsorbent canister has a housing defining an adsorption chamber therein, an adsorbent filled in the adsorption chamber, and a honeycomb core. The honeycomb core is made from a material having a higher thermal conductivity than the adsorbent, defines therein a plurality of cells passing through the honeycomb core and is disposed in the adsorption chamber. The adsorbent canister can further have a heater for heating the honeycomb core or the honeycomb core can be made from a material, which produce heat when current is applied.