A senior official told CNN the information included not only "white papers" on surveillance programs but also previously undisclosed information about the Foreign Intelligence Surveillance Court.
The official said the information could be revealed as soon as Tuesday.
The official said the release was part of a "concerted [and] deliberate" effort to declassify additional information in the wake of the leaks by former NSA contract worker Edward Snowden.
The moves come amid growing bipartisan congressional pressure to pass legislation that would change or possibly end some of the NSA's surveillance programs.
Director of National Intelligence James Clapper has been trying to declassify at least some detailed case opinions by the surveillance court, the official told CNN.
"I think there is a high likelihood of FISC opinions being declassified soon," the official said.
A DNI spokesman told CNN Monday the agency was "leaning forward and telling others to be more transparent as much as possible."
Snowden has been in a Moscow airport's transit zone since June 23 and has sought temporary asylum in Russia. He has been on the run since leaking information on NSA electronic surveillance programs.
Washington has called on Moscow to reject Snowden's request for asylum and return him to the United States for trial.
Notable deaths of 2014 [PHOTOS]