A series of novel carboxyl telechelic microspheres (CTMs) with different length of oligo-caprolactone telechelic chains are readily prepared via a three-step approach involving : (1) the hydrolytic oligomerization of epsilon-caprolactone, (2) the esterification of oligo-caprolactone with maleic anhydride, and (3) the suspension polymerization of maleic acid polycaprolactone ester acid (MAPCLA) with divinylbenzene. The CTMs, which are water swellable, spherical, and porous, contain carboxyl functionalities of 1.0 to 4.2 mEq/g (dry), which are found to be lower swelling change (during conversion of ionic form) and higher exchange efficiencies than those of the Emerk. IV resin.The intermediate products, oligo-caprolacton, and MAPCLA are characterized by the acid-base titration, hydroxyl value titration, and infrared and H-1 nuclear magnetic resonance analysis, respectively. The morphology and porous of CTMs are also tested by scanning electron microscopy and Brunauer-Emett-Teller technology. The effects of the length of the telechelic chains and the degree of crosslinking (divinylbenzene), as well as the amount of porogen (toluene), on the physical and chemical parameters of the CTMs are also described.