The Nexus One mobile phone is a slim, touchscreen phone built in partnership with Taiwanese manufacturer HTC and runs Google's Android operating system.
Direct from Google it will cost $529 (£331) and on contract with T-Mobile $179 (£112). Google said the phone would ship from launch day.
It will be sold via Google's website and initially be available on T-mobile in America followed by Vodafone in Europe and Verizon in the US.
Mario Queiroz, Google vice president for product management, described the launch as "the next stage in the evolution of Android".
Mr Queiroz said there were now more than 20 Android phones available from 59 carriers in 48 nations.
The release of the Nexus One is seen as a move to ensure Google remains relevant as people search the web using mobile phones rather than typing queries into a PC.
Google has set up its own phone portal through which people can get a handset tied to one of several mobile operators or untethered direct from the search firm.
Figures from Gartner suggest that Android has about a 3.5% share of the global smartphone market. By comparison Nokia has a 39% share and Apple 17%.
Google also announced on 5 January a plan to launch "pay to call" adverts that would appear on mobile phones. These would work in a similar way to the "pay to click" adverts that populate many websites and which form a significant chunk of Google's revenue.
Salient Features of Nexus One Phone
- 3.7 inch touchscreen
- 1GHz snapdragon processor
- 5 Megapixel camera with LED flash
- GPS and compass
- Accelerometer
- Noise cancellation technology
- Voice recognition can be used with all applications
- Light sensor changes screen brightness to conserve power
- 512MB Flash memory with SD card slot (expandable to 32GB)
