By Tarmo Virki, European Technology Correspondent
(Reuters) - Microsoft will double its share of the Western European smartphone market during 2012 to 12.3 percent, helped by its new partnership with Finland's Nokia, research firm Strategy Analytics said on Tuesday.
Nokia is scheduled to roll out its first smartphones using Microsoft's Windows Phone software platform on Wednesday at its annual media event in London.
Nokia decided to ditch the aging Symbian platform in favor of Microsoft's software in February 2011 in a risky deal which spooked investors.
Nokia's market value has since halved as investors are unsure whether it can ever regain the market share it lost.
The 12.3 percent forecast for Microsoft's software refers to its use across several mobile phone makers and compares to the much higher market share Nokia's Symbian platform alone previously enjoyed -- it controlled 41 percent of the West European market as recently as the first half of 2010.
Strategy Analytics said it expected Western Europe smartphone sales to reach 117 million units in 2012, growing 12 percent from this year, with Microsoft's Windows Phone being the fastest growing major platform.
"Due to growing support from leading hardware vendors, particularly Nokia, Microsoft is in a good position to become Western Europe's third major smartphone platform behind Android and Apple iOS next year," analyst Neil Mawston said in a statement.
The researcher expects Google's Android to capture 44 percent and Apple's iOS 23 percent of the market next year.
Strategy Analytics said the Microsoft platform would benefit also from Samsung Electronics and HTC promoting models using it, but cautioned that Microsoft's long-term success was not yet fully guaranteed.
"There remain several on-going challenges for Microsoft, including its limited support for high-growth dual-core superphones, the relatively modest size of its Marketplace apps store, and a consumer brand perception of Windows Phone that may have been tainted by the past weaknesses," Mawston said.
(Reporting By Tarmo Virki; Editing by Helen Massy-Beresford)