The oxidation kinetics of copper thin films have been studied at temperatures below 200 °C in air. The protection of copper from oxidation can be achieved by alloying copper film with Ti, Pd, Cr, or Al. The influence of the composition and microstructure to the oxidation rate has been studied. The compounds Cu3Ti, Cu3Pd, and CuAl2are stable in the oxidation ambient. The formation of Cr‐oxide, which is a passive oxide, explains the inhibition of oxidation on Cu‐Cr films. Compared with the crystalline phase, the amorphous Cu65Ti35alloy film is more oxidation resistant. A TiN layer with oxygen incorporated is more effective in preventing copper oxidation than a TiN layer without oxygen incorporated. A passivating Si3N4layer on copper thin films can prevent copper oxidation effectively at 350 °C in oxygen ambient.