Schiff base oligomer of N,N'-bis (2,4-dihydroxybenzylidene) 1,2-phenylenediamine (DHBPDA), with a double azomethine group, was synthesized from the oxidative polycondensation (OP) reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 degrees C. About 75% DHBPDA was converted to O-DHBPDA. The structures of the products were studied by UV-Vis, FT-IR, H-1-NMR, C-13-NMR and elemental analysis. According to Gel Permeation Chromatography (GPC) analysis of O-DHBPDA, the number average molecular weight (M-n), weight average molecular weight (M-w) and PDI values were found to be 4328 g mol(-1), 6228 g mol(-1) and 1.43, respectively. TG/DTA analyses were shown to be stable of O-DHBPDA against thermo-oxidative decomposition. During the polycondensation reaction, a part of the azomethine (-CH=N-) groups oxidized to aldehyde (CHO) group (10-12%). Oligomer-metal complexes of oligo-N,N'-bis (2,4-dihydroxybenzylidene) 1,2-phenylenediamine (O-DHBPDA) with Co(II) and Mn(II) were synthesized and characterized by FT-IR, UV-Vis, TG-DTA and Atomic Absorption Spectroscopy (AAS). The residue of DHBPDA, O-DHBPDA, O-DHBPDA-Co and O-DHBPDA-Mn were found to be 0%, 3.65%, 11.67%, and 9.20%, respectively at 1000 degrees C.