Jay Sullivan, who is heading up the project – codenamed Fennec – told the BCC that it is currently going through testing and could be released before the end of the year.
It will be able to synchronize with the desktop version of the browser – meaning any pages open on a Firefox user’s desktop will automatically open in the mobile version of the browser.
"At the end of the working day you can walk away from your computer and keep on going on your phone," Mr Sullivan told the BBC.
"It encrypts all of the information and sends it back through the cloud between your desktop and mobile."
If all goes to plan, before the end of the year he hopes N900 users will be able to download Firefox in Nokia’s Ovi store.
Mozilla, the parent company of Firefox, is also working on versions for Google’s Android and Microsoft’s Windows respective operating systems.
However, iPhone owners who like using Firefox on their desktop, will have to keep waiting to be able to sync their desktop and mobile browser experiences as Mr Sullivan told the BBC that Apple was a “pretty closed platform” so he didn’t see it happening soon.
Opera is the most popular mobile browser at the moment – as it is well optimised for the platform and comes pre-programmed into many mobile handsets