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Dielectric and conductivity spectra of the compound Li1−xNi1 +xO2 (x = 0.03) are reported and analysed. The spectra were recorded for compacted powders within the broad frequency range 10–1010 Hz at temperatures varying between 210 and 300 K. The evolution of the spectra of the sample with respect to the damage under air allows us to define two regimes: the first one is an interfacial regime and the second a bulk regime. The frequency of crossover (νco) between the two regimes lies in the interval 1 × 109 and 2 × 109 Hz at room temperature. At frequencies below νco, the spectral analysis shows dielectric relaxations due to interfacial polarization phenomena in the sample. The complex resistivity plots (for ν≤νco) allowed the determination of the dc conductivity of Li1−xNi1+xO2 versus temperature. At frequencies greater than νco, one dielectric relaxation corresponding to small-polaron hopping has been observed. The corresponding relaxation frequency is thermally activated with an activation energy of 0.15–0.16 eV and a pre-exponential factor ν0 ≈ 3 × 1012–4 × 1012 Hz, which is of the order of the longitudinal-optical-phonon frequency νLO. The conduction behaviour is interpreted in terms of hopping of small polarons (holes) on an oxygen network.