"Hot N Cold" is a song by American singer Katy Perry. The song was written and composed by Dr. Luke, Max Martin, and Perry for her second album, One of the boys.
The track was released as the album's third single. It reached number three on the Billboard Hot 100, making it Perry's second consecutive top three single, after her previous worldwide hit "I Kissed a Girl". The single has also become Perry's second top five single in dozens of countries around the world, including the U.K, Australia, Ireland and New Zealand, as well as topping the charts in Turkey, Finland, Germany, Greece, Canada, Norway and Denmark.