Krypton-85 is used in arc discharge lamps commonly used in the entertainment industry for large HMI film lights as well as high-intensity discharge lamps. The presence of krypton-85 in discharge tube of the lamps can make the lamps easy to ignite. Early experimental krypton-85 lighting developments included a railroad signal light designed in 1957 and an illuminated highway sign erected in Arizona in 1969. A 60 μCi (2.22 MBq) capsule of krypton-85 was used by the random number server HotBits (an allusion to the radioactive element being a quantum mechanical source of entropy), but was replaced with a 5 μCi (185 kBq) Cs-137 source in 1998.
Krypton-85 is also used to inspect aircraft components for small defects. Krypton-85 is allowed to penetrate small cracks, and then its presence is detected by autoradiography. The method is called "krypton gas penetrant imaging". The gas penetrates smaller openings than the liquids used in dye penetrant inspection and fluorescent penetrant inspection.
Krypton-85 was used in cold-cathode voltage regulator electron tubes, such as the type 5651.
Krypton-85 is also used for Industrial Process Control mainly for thickness and density measurements as an alternative to Sr-90 or Cs-137.
Krypton-85 is also used as a charge neutralizer in aerosol sampling systems.