Mozilla has announced details of the new “developer preview phones” that run its HTML5-based Firefox OS. The new OS has been eagerly awaited by developers ever since it was first announced in February last year. From next month, developers can get their hands on actual devices that run the OS, to enable them to better understand the software and test their apps. Expect a big splash at Mobile World Congress in Barcelona at the end of February.

The phones are being manufactured by Madrid-based Geeksphone in partnership with Telefonica, and are strictly for development purposes, they are not intended to be consumer models. There are two different models – the Keon and the Peak.

Both run on Qualcomm Snapdragon processors and operate over UMTS 2100/1900/900 as well as HSPA, EDGE and wifi. They pack 4GB of ROM and 512MB of RAM, have a microSD card slot, and feature a light and proxmity sensor, G-sensor and GPS.

The Keon simulates the more mass-market device, with a 1GHz processor, a 3.5-inch HVGA screen and 3MP rear camera. The Peak simulates the higher end of the market, with what appears to be a dual-core processor, larger 4.3-inch screen (described as “qHD IPS”), an 8MP rear camera and a 2MP front facing camera.

Stormy Peters, director of Websites and Developer Engagement at Mozilla, made the announcement on her blog, and invited developers to participate in Firefox OS App Days – a worldwide programme of over 20 hack days happening this week. She said that the developer preview phones will help make the mobile web more accessible to more people:

“Developers are critical to the web and to Mozilla’s mission to make the web accessible to everyone. Now we are working on bringing the power of the web to mobile, through Firefox OS, along with all the power of open standards and an open community, and once again, we’d like to invite web developers to join us.”

Keen developers don’t need one of the new phones to test out their Firefox OS apps though, as the firm has already uploaded a simulator to the Android Marketplace. No news on exactly when the developer phones will be available or how much they will cost.

Nick Dillon, senior analyst at Ovum, says one of the barriers to the success of Firefox OS will be cost:

“The Firefox OS devices will be targeted at emerging markets, where they will be competing with low to mid-tier Android devices. From a consumer perspective, the Firefox OS devices will offer less functionality than comparable Android devices, without access to embedded Google services and the hundreds of thousands of third-party applications available on Android devices. In order to be competitive and attractive to users, the Firefox OS devices will therefore need to be significantly cheaper than similar Android devices.”

It looks likely that the first consumer phones will be available, most likely in Latin America, for around $50 excluding operator subsidies. However, Dillon finds it “hard to believe” they will be able to achieve this price point, as they will be very similar in construction to comparable $150-$200 Android handsets. Hopefully we will get clarity on pricing models next month.