Research In Motion Ltd. is no longer the king of the U.S. smartphone market.

Smartphones running Google Inc.'s Android software outsold RIM's BlackBerrys in the United States in the three months ending January 2011, say new data from market tracking firm comScore Inc.

RIM's share of the U.S. smartphone market fell 5.4% to 30.4% in January, down from the 35.8% share the BlackBerry platform held at the end of October.

Meanwhile, Google's Android operating system - which runs on devices produced by several different manufacturers - saw its share of the U.S. smartphone market rise 7.7%, to 31.2% at the end of January from 23.5% in October.

RIM also saw its share of the overall market for mobile phones in the United States fall in the quarter.