The service will initially offer a selection of programmes rather than the complete schedule, and will be free to Sky subscribers who already have a Sky HD set-top box.
"The launch of Channel 4 HD represents an early cost-efficient entry into a valuable emerging market, and an important enhancement to the service offered to the rapidly increasing number of HD viewers," said Rod Henwood, director of new business at Channel 4.
"We believe that increased investment in HD at this stage could help boost HD production for the benefit of Channel 4 producers who will find their programmes more saleable in the international market."
The company plans to make the HD broadcasts available on digital cable TV and Freeview in the future.
"HD is transforming the TV experience and customers are responding in record numbers to the fundamental improvement in picture and sound quality," said Brian Sullivan, managing director of BSkyB.
"We want our customers to enjoy access to the widest choice of HD programmes, and we are extremely excited about the launch of Channel 4 HD.
"Be it sports, movies, documentaries or entertainment, Sky HD customers can now access the richest selection of content in HD."
Under the proposals the BBC will broadcast HD programmes on Freeview between 2am and 6am when spectrum is available.
The BBC will eventually want to broadcast nine hours of HD content on Freeview, but this will not be possible until the digital switchover is completed in 2012.
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