Low-frequency internal friction (IF) of pure copper after anodic polarisation (AP) in passivating sodium nitrite solution was studied. In the temperature range of 100–300 K a set of peaks was detected and they were recognised as the Hasiguti peaks. Excessive vacancy generation at the Cu\Cu2O interface was the reason for these peaks. It was assumed that excessive vacancies diffuse into the bulk metal and osmotic stress in copper caused by them results in dislocation multiplication and rearrangement of dislocation structure.