The electrical resistance of evaporated, high purity tin films deposited at 88°K decreases rapidly in two temperature regions as determined by isothermal annealing studies. One pronounced annealing peak occurs at 110°K and has an activation energy of 0.34±0.06 ev. The second much less pronounced peak at 180°K has an activation energy of 0.74±0.10 ev. The annealing characteristics of five pure films varying in thickness from 960 A to 4100 A and a film deposited in a high partial pressure of N2 are quite reproducible. The presence of O2 during evaporation, however, drastically altered the annealing kinetics and increased the activation energy at any given temperature. The defect resistivity at the time of evaporation was the same for all five pure films and a film deposited in a high partial pressure of N2, but is about 75 higher for the film deposited in the presence of O2. © 1961 The American Institute of Physics.