The performances of alumina-supported cobalt catalysts strongly depend on Co/alumina interactions, that are poorly understood. In the present work, alpha-alumina surfaces are used as models of polycrystalline support, to unravel their orientation dependent behavior by GI-EXAFS. The Co-II/alpha-alumina interactions in the dried state are investigated, with a resolution of the parallel versus perpendicular deposit formation. DFT calculations shed light on the existence of specific grafting modes. EXAFS shows that Co(OH)2 forms parallel to the R(1 (1) over bar 02), A(11 (2) over bar0) and M(10 (1) over bar0) surfaces, whatever the contact time (from 1 h to 6 days). However, a specific behavior of the C(0001) surface is observed. Whereas after one hour, the same parallel Co(OH)(2) is observed, at longer times it disappears while species exhibiting long then short Co-Co distances appear. The latter is assigned to epitaxial grafting of Co-II leading to a mixed phase, that is possible parallel to the C surface due to surface symmetry. (C) 2020 Elsevier Inc. All rights reserved.