The　fabrication　of　nanocomposites　by　covalent　inclusion　of　inorganic　nanoparticles　in　an　organic　polymer　matrix　is　highly　topical　and　may　find　applications　in　the　electronics,　optics　and　energy　sectors.　Incorporation　of　CdS　nanoparticles　into　the　polyacrylonitrile　(PAN)　matrices　could　be　expected　to　display　improved　or　enhanced　optoelectronic　and　optical　properties.　Using　a　newly　synthesized　RAFT　agent,　i.e.,　CdS-DDAT　nanoparticles　(DDAT:　S-1-Dodecyl-S-(α,　α′-dimethyl-α′′-acetic　acid)　trithiocarbonate),　CdS　covalently　functionalized　polyacrylonitrile　(CdS-PAN)　nanocomposite　material　was　prepared　in　the　presence　of　small　amount　of　AIBN　under　ultrasonic　radiation.　This　material,　which　exhibits　an　induced　positive　nonlinear　absorption　of　incident　light,　has　been　well-characterized　by　a　variety　of　physical　techniques　such　as　GPC,　UV/vis,　FT-IR,　TGA,　XRD　and　Z-scan.　©　2008　Elsevier　Ltd.　All　rights　reserved.