Net profit for the first quarter was $2.9 billion, or $2.27 per share, compared with $3 billion, or $2.09 per share, a year earlier.
Excluding $330 million on net special gains, earnings were $2.02 per share. That fell short of the analysts' average forecast of $2.08, according to Thomson Reuters I/B/E/S.
Refining and marketing profit fell to $452 million from $482 million a year earlier, while the oil and gas exploration and production arm's earnings, excluding one-time items, declined to $2.13 billion from $2.2 billion.
Oil and gas production totaled 1.64 million barrels of oil equivalent per day in the quarter, down 65,000 from a year earlier, but above the 1.62 million it had said earlier this month that it produced.
The decline was due largely to assets sales and the shutdown of a field in Bohai Bay, China, after a leak there, the company said.
Last week, ConocoPhillips said output from its oil and gas production arm would rise 3 percent to 5 percent annually, reaching 1.8 million barrels of oil per day by 2016.
The company's refining and marketing operations will be spun off into a stand-alone business named Phillips 66.
Shares of ConocoPhillips were down 1.9 percent at $71.50 in premarket trading.
The stock had risen slightly more than 1 percent through Friday's close, outperforming the drop of nearly 3 percent in the Chicago Board Options Exchange's index of oil companies <.OIX>.
(Reporting By Matt Daily in New York; Editing by Gerald E. McCormick, Dave Zimmerman and Lisa Von Ahn)