O2 is the second studio album by American boyband O-Town, following the success of their triple-platinum self-titled debut album.

The band was on the verge of obscurity, due to the public's taste of music changing. The album became a commercial flop. It peaked at #28 on the Billboard 200, and the lead single, "These Are the Days", only reached #64 and failed to match the success of "Liquid Dreams" or "All or Nothing". The second single, "I Showed Her", failed to chart anywhere. Despite a European tour and promotions for the album, it only reached Gold status and worldwide sales were half a million below sales of the self-titled album. The album showed more input from the band, as they co-wrote six of the songs. They soon disbanded the next year.