x-ray photoelectron spectroscopy has been used in order to follow the chemical changes of chemithermomechanical pulp (ctmp) fiber surfaces as the polyacrylonitrile (pan) grafting level increases, from 0 to 45 percent . the peak synthesis reveals that c1s peaks of the ungrafted and grafted ctmp samples are made up of three components-c/sub 1/, c/sub 2/ and c/sub 3/-while the c1s peak of the pure polyacrylonitrile is made up of only two c/sub 1/ and c/sub 2/ components and the n1s peaks are made up of two n/sub 1/ and n/sub 2/ components for both the ctmp grafted samples and the pure pan. the binding energies of the c1s components c/sub 1/ and c/sub 2/ of the grafted and non-extracted samples as well as those for the grafted and extracted samples are almost equal to those of the c1s peak of the pure polyacrylonitrile within +or-0.2 ev. the surface chemical modification of the ctmp fibers as a result of grafting is very well illustrated with diagrams representing the atomic oxygen and nitrogen fractions versus the grafting level