Microsoft sued Motorola on Friday claiming that the company's Android-powered phones infringed on nine patents held by the software giant.
According to a statement by Microsoft deputy general counsel Horacia Gutierrez, the alleged infringements centre on the way Motorola's phones synchronize email, calendars, contacts and meetings, and in the way it notifies the user of changes in signal strength and battery power.
Microsoft said it filed the action at the International Trade Commission and the US District Court in Washington.
"We have a responsibility to our customers, partners and shareholders to safeguard the billions of dollars we invest each year in bringing innovative software products and services to market," Gutierrez said.
"Motorola needs to stop its infringement of our patented inventions in its Android smartphones."
Microsoft did not name Google, which makes the Android operating system, as a party to the suit. Earlier this year Microsoft reached a software licensing agreement with another Android phone maker, HTC.
The action came as Microsoft prepares to launch its Windows Phone 7, which it hopes will rival Android and the iPhone in the smartphone market.