Trinuclear mixed-valence Co(III)-Co(II)-Co(III) complex {CoIII(μ-Sal2MePn)(N3)(μ1,1-N3)}2CoII(H2O)2 (I) was synthesized by the reaction of Co(NO3)2 · 6H2O with the Schiff base ligand H2Sal2MePn condensed from 2,2-dimethylpropylenediamine with salicylaldehyde and characterized by elemental analyses and FT-IR spectroscopy. The molecular structure of I has been determined from single-crystal X-ray diffraction analysis. In this structure, the N3− anions show both terminal and μ1,1-bridging modes. The terminal Co(III) centers exhibit uniform arrangements of the Schiff-base ligand and N3− anions.