To protect the HTS-thin film microwave-frequency passive and active de
vices from traces of acids and humidity in the atmosphere, the oxide s
uperconductors must be passivated. Electric parameters of the films an
d Q-factor of tile resonators have been measured before and after pass
ivation cycle, and thermocycles. The relative decrease of the critical
current density for different quality HTS films after passivation tre
atment is explained by water penetration between grains during imidiza
tion cycle.