"Sex on Fire" is the first single released from American rock band Kings of Leon's fourth studio album, Only by the Night. The song gave Kings of Leon their first number-one single in Australia, Finland, Ireland, and the United Kingdom, charting at the top spot on digital downloads alone in the latter country, before its physical release. In September 2009, it was Britain's second most-downloaded digital single ever.^[2] The song has sold 1.2 million copies in the United Kingdom as of November 2012.^[3] It has also gained significant popularity in the United States, reaching number one on the Hot Modern Rock Tracks chart and number 56 on the Billboard Hot 100, making it the band's second highest-charting song there on the latter chart.

In 2008, the song earned the band their first Grammy nominations. The song was nominated for Best Rock Song,^[4] and won the award for Best Rock Vocal Performance by a Duo or Group.^[5] In addition, the album earned a nomination for Best Rock Album. Channel V Australia named the song as the third biggest hit of 2008. It was voted number one in Triple J Hottest 100 countdown for 2008. Following the success of the follow-up single "Use Somebody" in the United States on pop radio, the track was re-serviced^[6] to US pop radio in November. Remixes of both songs were used for the runway soundtrack in the 2009 Victoria's Secret Fashion Show.^{[citation needed]}

Musically, "Sex on Fire" has been described as alternative rock.^[7][8] The song was written about lead singer Caleb's then-girlfriend (and now-wife), model Lily Aldridge.^[9] In an interview with Robbie, Marieke and the Doctor on Australian radio station Triple J, Nathan Followill explained that the band never intended the song to be named "Sex on Fire" and that it was not intended to be about sexuality.

They were totally different lyrics. Depending on whether a song starts with a melody or starts with lyrics, you know if it starts with a melody you just keep playing the melody over and over until you get it down and just throw in any lyrics that fit the verbal flow. It was actually going to be "Set Us on Fire", but one of the sound mixers in the studio walked in as we were playing and said, "'Sex on Fire', huh?" And it just kind of became a running joke, and we stuck with it.

Nathan also said that some lyrics tried were "Socks on Fire", "Snatch on Fire", and "Cocks on Fire".^[10] The song is played in the key of E major at a tempo of 153 bpm. The vocal range is B3–G♯4.^[11]

"Sex on Fire" received generally positive reviews. Digital Spy rated the song four stars out of five, describing it as "a truly stirring single that will be a definite highlight on their winter arena tour".^[12] Planet Sound also rated the song 9/10. However, Caleb Followill originally thought the song was "terrible";^[13] according to Spin Magazine, it was almost ditched during recording. Despite giving the album a 4 out of 5, Spin thought the song was "silly".^[13] The song was number 40 on Rolling Stone's list of the 100 Best Songs of 2008.^[14] The song was used for the trailer of the 2009 movie Stay Cool.^[15]

In 2016, Johnny Borrell of Razorlight called this song "the apex, death and afterlife of landfill indie all in one go" and noted its similarity to Stereophonics's "Dakota" from 2005.^[16]

In the United Kingdom, "Sex on Fire" entered the official UK Singles Chart at number one on September 14, 2008 ― for the week ending date September 20, 2008 ― and went on to an unbroken 42 weeks on the chart, only dropping out due to the surge in sales of Michael Jackson titles immediately after his death, but after a two-week absence it was back for another 37 weeks, re-entering the top 10 of the UK Singles Chart at number six in September 2009. Further reappearances extended its tally of weeks to 90, making it the third most charted single of all time.^{[citation needed]}

In Germany, the single debuted at number 97 on the German Singles Chart, and began to rise and fall in the next several weeks. In its 32nd week on the chart, the song finally reached its peak of number 33. As of February 2011, the song had been on the chart for 60 weeks, a huge effort for a single that did not reach the top 20. In February 2011, due to the long stay on the German Singles Chart, the single was certificated with Gold for more than 150,000 copies sold.^[17][18]

The director of the music video for "Sex on Fire" was Sophie Muller. In the video, the band is seen playing in a room at an abandoned factory. Other scenes show Caleb's brothers holding Caleb, who is tied to a mattress; Nathan washing his hair in a black water tub; Matthew explaining to Nathan and Jared about Caleb, and eating a chicken wing; and Caleb looking at strange shadows while lying on a soft mattress. At the end of the video, Caleb opens his mouth and smoke starts coming out of it.^[19]

7-inch vinyl

1. "Sex on Fire"
2. "Beneath the Surface"

CD single

1. "Sex on Fire"
2. "Knocked Up" (Live @ Oxegen '08)

In 2010, British singer-songwriter Tina Cousins released a dance version of the song.^[81]

• List of best-selling singles in Australia