The oxidative polycondensation reaction conditions of 4-[(pyridine-3-yl-methylene) amino]phenol (4-PMAP) were studied using H2O2, atmospheric O-2, and NaOCl oxidants in an aqueous alkaline medium between 30 degrees C and 90 degrees C. Synthesized oligo-4-[(pyridine-3-yl-methylene) amino] phenol (O-4-PMAP) was characterized by H-1-, C-13 NMR, FTIR, UV-vis, size exclusion chromatography (SEC), and elemental analysis techniques. The yield of O-4-PMAP was found to be 32% (for H2O2 oxidant), 68% (for atmospheric O-2 oxidant), and 82% (for NaOCl oxidant). According to the SEC analysis, the number-average molecular weight, weight-average molecular weight, and polydispersity index values of O-4-PMAP was found to be 5767, 6646 g mol(-1), and 1.152, respectively, using H2O2, and 4540, 5139 g mol(-1), and 1.132, respectively, using atmospheric O-2, and 9037, 9235 g mol(-1), and 1.022, using NaOCl, respectively. According to TG and DSC analyses, O-4-PMAP was more stable than 4-PMAP against thermal decomposition. The weight loss of O-4-PMAP was found to be 94.80% at 1000 degrees C. Also, antimicrobial activities of the oligomer were tested against B. cereus, L. monocytogenes, B. megaterium, B. subtilis, E. coli, Str. thermophilus, M. smegmatis, B. brevis, E. aero-ginesa, P. vulgaris, M. luteus, S. aureus, and B. jeoreseens. (c) 2006 Wiley Periodicals, Inc.