The local coordination of Fe3+ spin probes in trigonal LiAlyCo1-yO2 was studied using high-frequency electron paramagnetic resonance spectroscopy. This technique allows the determination of Fe3+ ions in respect to axial and rhombic zero-field splitting parameters (ZFS). After the progressive replacement of Co by Al, the axial D parameter of Fe3+ increases from +0.0548 to +0.2802 cm(-1). On the same order, the rhombic E parameter decreases. Structural information about the Fe3+ site in layered LiAlyCo1-yO2 oxides was based on modeling of the magnitude of the ZFS parameters by means of the Newman superposition model. It was found that the first metal coordination sphere including Co3+ and Al3+ ions gave rise to differentiation of the Fe3+ dopants in respect to local trigonal and rhombic distortion. The maximum trigonal distortion for the FeO6 octahedron was achieved when Fe3+ spin probes were surrounded by AI only, while the Co environment yields a rhombic distortion of the FeO6 octahedron.