Two new polynuclear azido-bridged Co(II) compounds with formulas catena-[Co(mu(1,3)-N-3)(N-3)(py)(2)(H2O)](n) (1) and [Co(mu(1,3)-N-3)(2)(4-acpy)(2)](n) (2) (py = pyridine, 4-acpy = 4-acetylpyridine) have been structurally and magnetically characterized. Compound 1 crystallizes in the orthorhombic system Fddd space group and consists of a single end-to-end azido-bridged chain with the Co(II) atoms in a CoN5O slightly distorted octahedron. Compound 2 crystallizes in the monoclinic system P2(1)/a space group and shows 2D sheets built up through end-to-end azido bridges with the Co(II) atoms in a CoN6 environment. The magnetic properties of 1 and 2 are reported. In the high-temperature region, the plots of chi(M) or chi T-M vs T for 1 and 2 compounds can be fitted by using the Curie-Weiss law, and the best-fit theta values are -69.1 and -22.6 K, respectively. For 2 magnetic ordering and spontaneous magnetization is achieved below T-c = 25 K.