As per the analysis of ComScore, Google Inc.'s Android mobile phone operating system’s U. S. market share has doubled, from September to December 2009.

Android's shares were reported to be at 5.2% in December, up from 2.5% in September, while BlackBerry maker Research In Motion Inc., Microsoft Corp. and Palm Inc. reportedly lost shares in the U. S. Smartphone market, during December.

Android, which was developed by Google and adopted by a number of hardware makers, has gained traction in recent months with the introduction of a number of handsets that use the software, including the popular Motorola Inc. Droid.

It is considered as Google's answer to Apple Inc.'s wildly popular iPhone, which was introduced almost three years ago. Apple's share of the U. S. smart-phone market rose to 25.3%, in December from 24.1%, in September.

ComScore also reported that Motorola maintained to be the top handset manufacturer in the U. S. market, despite the fall in its shares.

With more than 41% of the market share, Research In Motion, gained shares in the overall cellphone market.

A total of 234 million people aged above 13 years, in U. S., were reported to be using mobile devices, in December.