The Collaborative International Dictionary of English v.0.48:

chemosorption \chemosorption\ n.
   adsorption (especially when irreversible) by means of
   chemical instead of physical forces; as, chemosorption of
   gaseous nitrogen on iron catalysts.

   Syn: chemisorption.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

chemosorption
    n 1: adsorption (especially when irreversible) by means of
         chemical instead of physical forces; "chemisorption of
         gaseous nitrogen on iron catalysts" [syn: chemisorption,
         chemosorption]