Empyrean Group Inc., a Vienna-based Internet systems engineering firm, announced yesterday that it has purchased IconixGroup Inc., a Bethesda-based Web design firm, for $25 million in stock and cash.

Washington-based Iconixx Inc., as the merged company will be known, will offer comprehensive Internet services, including Web design, database maintenance and systems integration.

Thayer Capital Partners, a Washington venture-capital firm, ponied up $30 million to make the deal possible, doubling its investment in Empyrean to $60 million, said Rick Rickertsen, chief operating officer for the $1.2 billion fund.

"The industry sector they're participating in is growing at 40 to 50 percent" annually, Rickertsen said. Thayer decided to invest in the four-year-old Empyrean because of the management team's quality and breadth of experience, and he expects the company to grow at a 30 percent to 35 percent rate starting out, he said.

The firm, which will employ 300, will generate annual revenue of $60 million, Rickertsen said.

Stu Johnson, chief executive of Iconixx, said the company also secured a $40 million line of credit to help the company grow. Johnson, a former chief of Bell Atlantic Corp.'s information services group, was CEO of Empyrean.

Rickertsen said Thayer will focus on Iconixx's growth and will look to take the company public next year.