The Rouse Co.'s new chief executive, Mathias J. DeVito, said yesterday that he expects 1979 to be even better than last year, which was a record year for the Columbia-based firm.

DeVito was handed the reigns of the 40-year-old company from founder and Chairman James W. Rouse yesterday at the company's annual stock holders meeting.

Following the meeting, DeVito said that he and Rouse had developed a five-year plan that stresses continued developments such as the jointly developed community of Columbia and the Harbor Place project under construction in Baltimore.

The company is working on a number of other projects across the country, DeVito said, but he would not disclose what they were.

Rouse stepped down because the company's mandatory retirement rules required to him to do so at age 65, he told the stockholders. Rouse will continue as chairman of the board.

As an indication for the rest of the year, the firm reported a 43 percent increase in first quarter operating profits to $2.659 million from $1.859 million during the first quarter last year.

Earnings at the company's retail centers increased 18 percent to $3.610 million from $3.051 million in 1978.

"We feel very good about the first quarter," DeVito said.

The company also opened more projects last year than in any other year, he added. Those projects are the expansion of the Cherry Hill mall in New Jersey, Augusta Mall in Augusta, Ga., Beachwood Place near Cleveland, two Clover Square mini-malls in Pennsylvania and New Jersey, Faneuil Hall Marketplace in Boston and Woodbridge Center in New Jersey.

The Rouse Investing Co., which the firm is liquidating, "is no longer a problem for the Rouse Co.," DeVito said. "It's losses will continue to go down." Losses during the first quarter were $43,000 compared with $63,000 for the 1978 first quarter.

One stockholder, however, was not as pleased with the company's success. A tenant of the Cross Keys, a multi-use community project in Baltimore, complained that the company had raised his rent for office space beyond the president's wage and price guidelines. Rouse said the company had not exceeded the guidelines.

Along with the responsibility for the company's future, Rouse gave DeVito, 48, a Bible, a verse and a wall hanging that reads: "When life gives you lemons, make lemonade." Rouse also gave Mathias, amidst laughter of about 300 stockholders present, a frozen can of lemonade in case "resources run a little low."