A new heterometallic complex {[CoSr(2,3-pdc)₂(H₂O)₅]3H₂O}_n (1), where 2,3-H₂pdc stands for 2,3-pyridinedicarboxylic acid, has been synthesized and investigated by single crystal X-Ray diffractometry, IR spectroscopy and thermal analysis. The compound is self-organized in a polymeric structure forming a 2D framework. The 2,3-pyridinedicarboxylic acid is fully deprotonated performing several types of coordination: monodentate, bridging chelating, bidentate bridging. Thermal decomposition of the heterometallic 2,3-pyridinedicarboxylate 1 leads to the formation of a perovskite type oxide of brownmillerite series, 2, with 20.8 % yield. Magnetic studies of 1 show the paramagnetic behavior of Co(II) ions with a significant influence of a ground state zero-field splitting at low temperatures. Variable field and temperature magnetic studies of the oxide product 2 (obtained by the controlled heating of 1) indicate the presence of the Sr₆Co₅O₁₅, detected by the diffraction method. Also, trace amounts of SrCoO_2.75 and SrCoO_2.5 were revealed by magnetic and DSC methods, respectively.