The effect of Re on the composition distribution and structure of Co-Re-P and Co-Re-Ni-P electroless coatings is studied. he participation of disproportionation reactions during perrhenate reduction to the elemental state, coupled with the two-electron reduction of Re(VII) to Re(VI) by hypophosphite, is proposed as an explanation for the mechanism of Re codeposition. This also gives an explication of the increased efficiency of hypophosphite in the presence of perrhenate, and the observed extremely low P percentage in the coatings. The deposits have a hexagonal close-packed (hcp) lattice with a texture < 10 (1) over bar0 >. Uniform cross sections of the films, prepared by the focused ion beam technique, are used to characterize the nanocrystalline columnar structure in relation to the composition distribution by applying high-resolution analytical electron microscopy. Besides the partial localization of Re at the grain boundaries, it is alloyed with Co and Ni within the crystalline grains. This could be considered as evidence of two possible ways of Re inclusion in the alloys. The parameters of the hcp lattice increase with the Re content in the alloys. The impact of Re and its distribution in the nanocrystalline structure on the magnetic properties of the coatings is demonstrated. (c) 2008 The Electrochemical Society.