  The novel spin-chain cobalt oxide Sr5Pb3CoO12 [P-62m, a = 10.1093(2) A and c
= 3.562 51(9) A at 295 K] is reported. Polycrystalline sample of the compound
was studied by neutron diffraction (at 6 and 295 K) and magnetic susceptibility
measurements (5 to 390 K). The cobalt oxide was found to be analogous to the
copper oxide Sr5Pb3CoO12, which is comprised of magnetic-linear chains at
inter-chain distance of 10 A. Although the cobalt oxide chains (mu_eff of 3.64
mu_B per Co) are substantially antiferromagnetic (theta_W = -38.8 K), neither
low-dimensional magnetism nor long-range ordering has been found; a
local-structure disorder in the chains might impact on the magnetism. This
compound is highly electrically insulating.
