Google announced on Tuesday that it has closed the 12.5 billion-U.S. dollar acquisition of Motorola Mobility.

"I'm excited to announce today that our Motorola Mobility deal has closed. Motorola is a great American tech company that has driven the mobile revolution, with a track record of over 80 years of innovation, including the creation of the first cell phone," Larry Page, Google co-founder and chief executive officer, wrote in a blog post.

Motorola Mobility's Sanjay Jha will step down as CEO and Google Senior Vice President Dennis Woodside will lead the cellphone company, according to the post.

"It's a well known fact that people tend to overestimate the impact technology will have in the short term, but underestimate its significance in the longer term," wrote Page.

"Many users coming online today may never use a desktop machine, and the impact of that transition will be profound -- as will the ability to just tap and pay with your phone. That's why it's a great time to be in the mobile business."

Google announced to acquire Motorola Mobility for 12.5 billion dollars in August, with a purchasing price 63 percent premium over Motorola's closing price on the day when the deal was announced.

The deal then had to be approved by a series of regulators around the world.

Motorola Mobility's patent portfolio is seen as the main reason for the acquisition, as Google, along with its manufacturing partners, are fighting legal battles with companies claiming that Google's Android platform violates patents.

However, there have been concerns that the software-hardware bundle may not work for Google as it did for Apple. And it may also affect Google's partnership with other manufacturers as Google may favor its own hardware play in the future.

Motorola has around 19,000 employees, about 60 percent of Google's working force. Technology news site TechCrunch reported on Monday that Google is considering laying off some Motorola employees after the deal is closed.