COSTA MESA — Philanthropist Henry Segerstrom will give $40 million for the construction of a 2,000-seat concert hall here, in what may be the largest single charitable cash gift in Orange County history.

“I want my gift to be an investment in performing arts that will inspire cultural growth into the future,” Segerstrom told nearly 200 board members, donors and potential donors at the Orange County Performing Arts Center on Thursday.

The Segerstrom family, the farming dynasty that owns South Coast Plaza, donated the land and $6 million for the existing center and the South Coast Repertory theater more than 20 years ago with the vision of creating a complete arts center in the city’s South Coast Metro neighborhood.

Henry Segerstrom also donated six additional acres for the expansion, a parcel valued at $13.2 million, according to officials from the Orange County Performing Arts Center.

“We are no longer talking about maybes,” said Roger Kirwan, chairman of the board of the Orange County Performing Arts Center, “but a reality. An imminent reality.”

In addition to an acoustically state-of-the-art concert space, the Renee and Henry Segerstrom Concert Hall — named for the donor and his late wife, who died in June — will feature a 500-seat multipurpose hall and a central public plaza.

Mark Chapin Johnson, vice chairman of the center’s board of directors, said with the Segerstrom donation, the board had already raised $65 million for the $200-million project, which is scheduled to open by late fall 2004.

“This center will be the catalyst of what will make this community and world know what we’re all about,” he said.

Johnson was one of four speakers, including Carl St. Clair, maestro of the Pacific Symphony Orchestra, who toasted and gushed praise onto Segerstrom.

Segerstrom also used the gathering to introduce his new wife, Elizabeth, 45, to the public.

He married the clinical psychologist and self-help book author late last month.

“Henry has the most incredible dedication to this project,” said Elizabeth Segerstrom, dressed in a lime green suit. “We’re all very excited.”

FYI

Other large individual donations to Orange County institutions:

* 1999: Henry Samueli, co-founder of chip maker Broadcom Corp., donated $20 million to UC Irvine’s engineering school.

* 1999: An anonymous donor gave a $20-million donation to Chapman University.

* 1998: Scientist and philanthropist Arnold Beckman donated $14.4 million to Orange County’s elementary schools for expanding and improving science programs.