Just 18 per cent of internet users in the UK use the open source browser, compared to nearly 50 per cent in Finland and Slovenia.
Although this was up over two per cent on last year, UK take-up of Firefox remains slow.
"The use rate for Firefox in all of the European countries within the study increased from 23.2 per cent to 24.1 per cent between November 2006 and March 2007," said XiTi Monitor.
"The Czech Republic achieved the greatest increase in points, from 26.7 per cent to 31.5 per cent.
"Among the 30 European countries studied, five decreased in relation to November 2006: Hungary (down 3.9 points), Denmark (1.7 points), Estonia (1 point), Holland (0.7 point) and Italy (0.5 point)."
Europe has lost its position as the top user of Firefox to Australasia, where growth is stronger than anywhere else in the world.
Firefox is used by 24.1 per cent of Europeans, compared to 24.8 per cent in Australasia. South America and Asia polled lowest with fewer than one in eight users.
XiTi Monitor also compared the take-up of Firefox 2 compared with Internet Explorer 7, both of which were launched in 2007.
The data showed that Firefox users were quicker to upgrade to the new browser. Nearly two thirds had upgraded by the end of the year, compared to fewer than half of Internet Explorer users.
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