Coldplay's album Viva La Vida or Death and all his Friends is out in June
There was "massive demand" for the new Coldplay single, available as a free download, which caused problems for some fans who rushed to hear it.
Violet Hill was made available from the band's website at 1215 BST on Tuesday.
A spokesman described the response as "incredible", adding: "Massive demand slowed everything down in the first 40 minutes of the download going live.
"But that was quickly fixed and Coldplay.com is delivering tracks to fans at full speed."
Violet Hill is the first material to be heard from the band's fourth album Viva La Vida or Death and all his Friends, which is out on 12 June.
In an online poll of 1,400 people on the Coldplaying fan site, some 60% gave the song nine or 10 out of 10.
The band are still to announce details of three free concerts - in London, New York and Barcelona.