Refinement of the structure of Na-0.74(2)CoO2 was carried out using neutron diffraction data. The material was indexed using the hexagonal P6(3)/mmc space group with lattice parameters a = 2.840(1) Angstrom and c = 10.811(1) Angstrom. High resolution neutron powder diffraction data of the layered metal oxide were analysed ab initio to reveal a structure with alternating sodium layers intercalated between octahedral sheets of cobalt oxide (CoO,). The two sites available for occupancy by the sodium ion in the sodium layer of the unit cell are (2/3, 1/3, 1/4) and (0, 0, 1/4). The sodium ions occupy the two available sites unequally (the probability of finding sodium ions at one site being approximately twice that for the other site) due to the influence of second nearest neighbour cobalt ions.