SAN FRANCISCO -- Robert Dynes, the former University of California, San Diego chancellor who has served as president of the 10-campus University of California system since 2003, announced Monday that he will step down next summer.

"I depart knowing that the university, at its core, remains strong," said Dynes, 64. "And that is because of the dedication, hard work and vision of its faculty, staff and students. They represent the foundation on which this great university has been built, and for that I express my heartfelt thanks to our entire community."

UC Provost and Executive Vice President Wyatt R. Hume was appointed immediately as UC's chief operating officer, a post he will maintain until a new president is named. Dynes will step down by June 2008.

The UC Board of Regents is expected to appoint a search committee shortly to oversee a national hunt for a new system president.

"During his time of leadership, the UC community has continued the journey to an even better university," said Richard C. Blum, chairman of the Board of Regents. "Initiatives have been launched to begin addressing critical problems in the areas of diversity, K-12 educational disparity and salary gaps. And we have laid the groundwork for the restructuring of the university's administrative infrastructure to create a more effective and efficient organization."

Dynes served as UC San Diego's chancellor from 1996 until his selection as UC president in 2003. He was initially hired at the university as a physics professor in 1990, following a 22-year career with AT&T Bell Laboratories, where he headed semiconductor and material physics research.

He founded a research lab on the UCSD campus and eventually became chairman of the physics department and senior vice chancellor for academic affairs before taking over as chancellor.

UC officials credited Dynes with helping to improve the university system's long-range planning, but he also dealt with well-publicized questions about the system's executive compensation disclosure practices, along with concerns about the diversity among students and faculty.

"I consider this an area that should be of utmost importance to my successor and the overall leadership of the University of California," Dynes said.

Gov. Arnold Schwarzenegger called Dynes a "great partner."

"Under Bob's leadership, he enhanced the prestige of California's world-renowned UC system," Schwarzenegger said. "For his dedication and commitment to to the students, the UC system and the state, he will be missed. I appreciate all his years of service as president and wish him the best of luck in the future."