In this study, the oxidative polycondensation reaction conditions of 2-hydroxyphenylbenzaldimine (HPBA) with air oxygen and NaOCl were studied in an aqeous alkaline medium between 50 and 90degreesC. The product was characterized by H-1-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC), and element analysis techniques. Solubility testing of oligo-2-hyroxyphenylbenzaldimine was investigated by organic solvents such as DMF, THF, DMSO, methanol, ethanol, CHCl3, CCl4, toluene acetonitrile, ethyl acetate, conc. H2SO4, and aqueous alkaline solution. 2-Hydroxyphenylbenzaldimine (96%) was converted to oligomer by oxidation in an aqueous alkaline medium. According to solubility in water, oligo-2-hydroxyphenylben-zaldimine separated into two fractions: oligo-2-hydroxyphenylbenzaldimine (OHPBA-1, undissolved in water) and oligo-2-hydroxyphenylbenzaldimine (OHPBA-II, dissolved in water). According to the SEC technique, the number average molecular weight (M.), mass average molecular weight (M,), and polydispersity index (PDI) values of OHPBA-1 and OHPBA-II were found to be 2166 g mol(-1), 2591 g mol(-1), and 1.196; 1736 g mol(-1), 2509 g mol(-1), and 1.445, respectively. Also, differential thermal analysis (DTA) and thermo gravemetric analyses (TGA) were shown to be stable of oligo-2-hydroxyphenylbenzaldimine against thermo-oxidative decomposition. The weight loss of OHPBA was found to be 93.63% at 1000degreesC.