Christopher Boyce, 24, a college student who said he was blackmailed into selling American secrets to the Soviet Union, was convicted this afternoon on all eight counts at his trial here for conspiracy, theft and espionage.

Boyce sat impassively in a rust-colored suit, his hand on his chin, as a clerk read the verdict. His attorney, William Dougherty, said he would appeal.

The verdict came less than five hours after the jury received its final instructions from U.S. District Court Judge Robert Kelleher.

Kelleher scheduled Boyce's sentencing for May 27. Although the espionage act calls for a possible death penalty, U.S. Attorney Richard Stilz said his office would seek a life sentence for Boyce because of recent Supreme Court decisions outlawing the death penalty.

Boyce and his longtime friend, Andrew Lee, 25, were arrested by the FBI in January for allegedly selling classified CIA documents to Soviet agents. Boyce, formerly a classified document clerk at TRW, a large electronics firm at Redondo Beach in suburban Los Angeles, had access to CIA-contracted studies, and allegedly gave them to Lee, who in turn allegedly sold them to the Soviets for an estimated $76,000.

The allegations at the trial centered around the "Pyramider" project documents found on alleged co-conspirator Lee's person when he was arrested by Mexican authorities in January.

Boyce allegedly gave Lee a microfilm copy of a 1973 study, contracted by the CIA to TRW for $66,000 on the feasibility of Pyramider, an elaborate communications satellite program proposed by the Central Intelligence Agency but subsequently dropped.

Lee's trial started Wednesday morning. His defense counsel, Kenneth Kahn, charged in his opening remarks that Boyce was "a CIA operative" and that Lee was unwittingly involved in the spying of his friend Boyce, who told him that the documents given to the Soviets were meantonly as "disinformation."

Boyce's lawyer, Dougherty, said after the verdict that his client was pleased that out of his trial some revelations concerning CIA activities in Australia had been revealed. On Tuesday Boyce told the court of an alleged CIA plot in 1974 to subvert Australian labor unions.

No one in Boyce's family was on hand today when the verdict was announced. Boyce, whose father is a former FBI agent, has refused visits from his family or friends since his arrest.

"Chris is a personable, deep-thinking guy, and there's a lot of embarrassment involved in this," said assistant defense counsel and longtime family friend George Chelius. "He doesn't want anyone to see him handcuffed or the bars around those prison walls."