The smartphones, Keon and Peak, are being developed by Geeksphone in partnership with Telefonica, according to Mozilla.
Stormy Peters, Mozilla's Director of Websites and Developer Engagement, said: "Firefox OS is a new mobile operating system built entirely using open web standards. In Firefox OS, HTML5 apps can do “phone things” – they can make the phone vibrate, make a phone call or send a text message."
The Keon model has a 3.5” HVGA multi-touch screen, three megapixel camera 4GB ROM and 512MB RAM. It comes unlocked, meaning any SIM can be installed.
The Peak model has 4.3” qHD IPS multi-touch screen, front and back cameras, 4GB ROM and 512MG RAM.