The local coordination of low-spin Ni3+ probes in trigonal LiAlyCo1-yO2 was studied using high-frequency EPR spectroscopy. This technique allows distinguishing-between two types of Ni3+ ions: Ni3+ ions in trigonal crystal field (E-2(g) ground state) and Ni3+ ions in tetragonal crystal field ((2)A(ig) ground state). When a Ni3+ ion is in a uniform Co environment, the orbitally degenerate state for Ni3+ is preserved and the EPR spectrum of the ground vibronic doublet state can be observed (intermediate Jahn-Teller effect). The value of g(1) decreases as the mean M-O bond is contracted. The local tetragonal distortion can be observed for Ni3+ ions located in a mixed Co6-yAly environment. Along the progressive replacement of Co by Al, the strength of the crystal field for Ni3+ increases gradually and the extent of the tetragonal distortion displays a tendency to increase. The maximum effect of Jahn-Teller distortion is achieved when the Ni3+ ion falls in a pure Al environment.