Conjuge bonding oligosalicylaldehyde-graft-oligoaniline (OSA-graft-OA) was synthesized from the polycondensation reaction of oligosalicylaldehyde (OSA) with oligoaniline (OA). There were various functional groups such as -OH, -NH and -CH=N in the structure of the graft cooligomer. The physical properties of graft-cooligomers such as melting temperature and solubility were studied: number-average molecular weight, mass-average molecular weight, and a polydispensity index of OA, OSA, and fractions of the graft cooligomers [(OSA-graft-OA)-I] and [(OSA-graft-OA)-II] were found to be 740, 780 g mol(-1), 1.05: 3700, 5990 g mol(-1), 1.62; 990, 2770 g mol(-1), 2.80 and 1300, 4100 g mol(-1), 3.15, respectively. The FTIR and UV-Vis spectra of the graft cooligomer were compared with those of beginning oligomers. The spectral analyses results showed that the OSA-graft-OA synthesized from the polycondensation reaction of aromatic amine with aldehyde that have long oligophenol macromolecule bonded each other with an azomethine bridge through oligophenylamine side chains. The thermal stability of the graft cooligomer and oligomers were measured by thermogravimetric analysis (TG) under an air atmosphere. According to TG analyses, the carboneous residues of the [(OSA-graft-OA)-I] (soluble in ethanol) and (OSA-graft-OA)-II) (soluble in toluene)] were 23 and 40%, respectively, at 1000degreesC. (C) 2002 Wiley Periodicals. Inc.