The coordination of Ni2+ ions to lattice oxygens in calcined X and Y zeolites has been extensively studied. A survey of the literature is presented here. From X-ray diffraction, Ni2+ ions are known to occupy preferentially the hexagonal prisms (SI) in octahedral symmetry. The main d-d absorption bands of Ni2+ ions in calcined NiX and NiY were assigned on this basis. The corresponding low value of the crystal field (10Dq approximate to 6400 cm(-1)) was accounted for by unusual long Ni-O bond lengths at S-I sites. We demonstrate here that this assignment is not consistent with recently reported extended X-ray absorption fine structure measurements End that the absorption bands should be reassigned to Ni2+ cations in distorted tetrahedral and trigonal (D-3h) coordinations. These cations are located in the supercages and/or sodalite cavities.