El Pollo Loco earnings: 18 cents per share vs. expected EPS of 17 cents

An El Pollo Loco restaurant is shown in San Diego, California
Mike Blake | Reuters
An El Pollo Loco restaurant is shown in San Diego, California

Restaurant chain El Pollo Loco reported quarterly earnings and revenue that topped analysts' expectations on Thursday, but its stock slipped in extended trading on weaker-than-expected comparable restaurant sales and guidance.

The company posted adjusted first-quarter earnings of 18 cents per share, up from 13 cents in the year-earlier period. Revenue came in at $90.4 million, up from $81.4 million.

Wall Street had expected the company to deliver quarterly earnings per share of 17 cents on $88 million in revenue, according to consensus estimates from Thomson Reuters.

"We are very pleased with our first-quarter results, which once again demonstrate strong operating momentum through solid sales and earnings growth," said Steve Sather, president and CEO of El Pollo Loco, in a release.

Read MoreHere's Pollo Loco's key to success, its CEO says

Comparable restaurant sales grew 5.1 percent, below analyst expectations for 5.5 percent.

El Pollo Loco projects adjusted earnings per share of between 67 and 71 cents for the year, with comparable restaurant sales growth of 3 to 5 percent. Wall Street had expected 2015 earnings guidance of 70 cents per share.

The company's shares plummeted more than 10 percent in after-hours trading.

The chain expects to open 16 company-owned restaurants and 11 franchised locations for the year. It will be expanding to Utah and then to the Houston area. El Pollo Loco has more than 400 company-owned and franchised restaurants in Arizona, California and Nevada.

"We remain excited about the opportunity ahead to expand in both new and existing markets," Sather said.

The company's stock spiked nearly 60 percent in its market debut last July. The shares had jumped almost 20 percent since the closing price of $24 on its first day of trading.

CNBC's Reem Nasr and Reuters contributed to this report.