The fourth season of the American television series Bones premiered on September 3, 2008 with a two-hour episode and concluded on May 14, 2009 on the Fox Network. The show changed time slots again, airing on Wednesdays at 8:00 pm ET before moving to Thursdays at 8:00 pm ET in 2009. The season consisted of 26 episodes and averaged 10.8 million viewers. In the UK, the season premiered on September 25, 2008 and concluded on May 28, 2009 on Sky1, and averaged 827,000 viewers.