Mozilla announced a pair of “Firefox OS developer preview phones”, as it looks to build up developer support for the fledgling platform ahead of commercial availability.

The devices have been created by Geeksphone and Telefonica, the operator which has been one of the most prominent supporters of Firefox OS.

In a blog post, Mozilla made much of the web credentials of the new devices, which use an operating system that is largely based on HTML5.

The company noted: “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.”

It is also holding a number of “hack days“, where technology specialists and developers from Mozilla will showcase tools and technology built to extend and support the platform, including APIs to provide access to device features.

The challenge the company will face is in generating developer support for a platform that has yet to be used in a commercial device – and which therefore has no users.

Telefonica is expecting to offer the first device via its Vivo subsidiary in Brazil imminently.

Research firm Strategy Analytics said that the platform is likely to secure a “niche” 1 percent of the market in 2013, meaning it is likely to be of limited interest to developers who are already not short of choice in the smartphone market.

However, with the platform being HTML5-based, it does use a number of technologies already familiar to web developers.

HTML5 is also being positioned as a way to deliver apps and content to a wide range of smartphone users, across platforms.

This means that Mozilla will be able to court existing web developers as well as capitalising on one of the major trends for smartphone apps, in order to deliver a wide range of content to users.

Two developer devices are available: Keon and Peak.

The former is a cheaper option, with 1GHz Qualcomm processor, 3.5-inch screen and three megapixel camera, while the latter has a 1.2GHz dual core Qualcomm processor, 4.3-inch screen and eight megapixel camera.