Positive muon spin rotation experiments for polycrystalline Cu and Al from 19K to temperatures near the melting points are reported. At low temperatures, the depolarization associated with localization of the muons at octahedral interstitial sites is seen in Cu, while in Aℓ only slight depolarization is observed below 250K. At high temperatures, no evidence for trapping of positive muons at vacancies in thermal equilibrium is found for either metal. It is concluded that the muons either diffuse... »