X-band EPR of LaSrAl 1−x Ni x O 4+δ ceramics (x=0.4–0.6 and 1) was studied over the temperature range 4.2–300K. The observed EPR signals corresponding to ∼0.01 of the introduced nickel ions are interpreted in terms of the JT effect of the low-spin Ni 3+ configuration (3d 7 , S= 1 2). Measurements of magnetic susceptibility of LaSrAl 0.5 Ni 0.5 O 4+δ over the 1.75–300K temperature range allow to conclude that all nickel ions are in the low spin state in those ceramics. Exchange interactions with zJ′ Ni–Ni =−11.6cm −1 was found. The EPR spectra analysis reveals that Ni 3+ ions are situated in axially distorted octahedron characteristic for the Al-phase (g ⊥ (1) =2.232±0.002; g || (1) =2.033±0.002) but there also exist sites with cubic symmetry of local crystal field in Ni-phase (the signal with g ⊥ (2) =2.211±0.002 and g || (2) =2.039±0.002 at T<10K which are averaged to isotropic signal with g (3) =2.155±0.001 in 10–90K temperature range). An important role of interstitial oxygen generating the local cubic symmetry sites in the process of structure relaxation to an equilibrium state after preparation of the samples or after annealing at 600°C was proved.