Historian Stanley Kutler told The Washington Post the Nixon Presidential Library and Archives in California will release a series of recordings and documents in addition to the grand jury transcript.
Kutler was among a group of historians who sued to make the materials available to the public.
Previously Nixon's testimony had been redacted under laws that shield grand jury materials.
Steven Aftergood, who directs the Project on Government Secrecy for the Federation of American Scientists, called the upcoming release "a missing piece or the puzzle about the Nixon administration."
"It's not often you get to hear a president under oath answering questions about misconduct," Aftergood said.
The grand jury was investigating the June 1972 break-in at Democratic National Committee headquarters at the Watergate complex in Washington.
Nixon resigned the presidency Aug. 9, 1974, as a result of efforts to cover up a White House role in the break-in.