James C. Warf, a professor emeritus of nuclear chemistry considered a “citizen scientist” because of his work toward world peace, died Nov. 7. He was 91.

Warf, who joined USC College in 1948 and retired 40 years later, remained an active scholar until shortly before his diagnosis of metastatic cancer of the spine in June.

He died at his home in Franklin Hills, surrounded by his family, said his son Curren Warf, associate professor of clinical pediatrics at the Keck School of Medicine of USC.

In 2001, Warf earned a USC Faculty Lifetime Achievement Award and USC Distinguished Emeriti Award.

“My father was a very gentle, intelligent man who was concerned about poverty and human suffering,” his son said. “He was sincere in trying to make a difference.”

A Ph.D. student at Iowa State University in the mid-1940s, Warf was a leader of the analytical and inorganic chemistry sections on the Manhattan Project, which developed the first nuclear weapons during World War II.

After the United States’ atomic bombings of Hiroshima and Nagasaki in 1945, he helped found the Federation of American Scientists, created to warn public and policy leaders of the dangers of nuclear proliferation.

In February, months before his diagnosis, Warf co-wrote “The Future of Nuclear Power,” which was published in the Monthly Review. The article argued against the building of new nuclear plants to help offset global warming, a solution proposed by some, because it would create an enormous hazard to the earth, generating radioactive waste lasting for untold years.

“The most important principle of environmental thought is that of safeguarding the earth for future generations,” Warf wrote. “To turn to nuclear power as a solution to global warming would be to abandon that trust.”

Larry Singer, professor of chemistry at the College since 1967, said that Warf was deeply devoted to his students, and he felt an obligation to educate the public at large and become a spokesperson for the sciences.

“I think of James Warf as a ‘citizen scientist,’ ” Singer said. “He was a humanist. He really cared about humanity.”

Warf, who held four patents on techniques to extract plutonium from nuclear fission waste, became an activist after the method was used to proliferate nuclear weapons worldwide.

“He came to see the inherent dangers and began working toward world peace,” Singer said.

He gave lectures worldwide on nuclear disarmament, testified before congressional hearings and in 1994 traveled to Kazakhstan with a team investigating the former Soviet nuclear warhead test site and health problems resulting from radioactive fallout.

After more than 50 years researching the chemistry of radioactive materials, he wrote All Things Nuclear (Figueroa Press, 2005), a 732-page book detailing all manifestations of radioactivity.

“But he was not anti-nuclear,” Singer said. “One has to be very clear on that.”

Warf advocated nuclear technology for positive uses such as radiation therapy for cancer, Singer added.

Warf was also a linguist and world traveler, spending a cumulative total of nine years in Indonesia and Malaysia, where he taught chemistry and wrote text books.

“He had an international view of his work,” said David Dows, professor emeritus of chemistry, who joined the College in 1956. “He was sympathetic to all people.”

Born Sept. 1, 1917, in Nashville, James Curren Warf Jr. was the youngest of three children. His family moved to Troy, Tenn., before settling in Tulsa, where he thrived in science since boyhood.

At Iowa State University, he met and eventually married Lee Walker, who taught piano and elementary school. Warf studied for a year in Switzerland on a Guggenheim fellowship before his arrival at USC. Warf and his wife had three children before Lee Warf died in 1959.

In 1966, Warf married Kyoko Sato and continued his teaching and peace activism.

Warf is also survived by daughter Sandy Warf of Seal Beach; son Barney Warf of Lawrence, Kan.; three grandchildren and a great-grandchild.

A memorial service will be held Dec. 13 from 2 to 4 p.m. in the Vineyard Room at the Davidson Conference Center.

Contributions in his name may be made to the Recording for the Blind & Dyslexic. For four decades, Warf read chemistry texts for the organization.