"Americans should have easy access to the results of research they help support," John Holdren, the director of the White House Office of Science and Technology Policy, wrote on the White House website.
An online petition on the White House website demanding free access over the Internet to scientific journal articles arising from taxpayer-funded research drew 65,704 signatures.
The directive comes amid a changing landscape for publishing and the availability of information due to the Internet.
Scientists have long published the results of their work in scholarly journals, and many such publications have warned that open access would destroy them and the function they provide the scientific community.
The White House move also came some six weeks after the suicide of Internet openness activist Aaron Swartz, who was renowned for making a trove of information freely available to the public.
Swartz ran into trouble in 2011 when he was indicted by a federal grand jury on charges related to allegedly stealing millions of academic articles and journals from a digital archive at the Massachusetts Institute of Technology.
The activist, who pleaded not guilty to all counts, faced a lengthy prison sentence and a hefty fine if convicted in a trial that was set for later this year.
Swartz's family and supporters blamed prosecutors for overreaching in his case, and his suicide drew attention to questions about the 1984 U.S. computer fraud law, much of which was written before the Internet.
Holdren said the decision to provide greater access took the concerns of scientific journals into account.
"We wanted to strike the balance between the extraordinary public benefit of increasing public access to the results of federally-funded scientific research and the need to ensure that the valuable contributions that the scientific publishing industry provides are not lost," he said.
Federal agencies are permitted a 12-month embargo time before offering access and can petition for a longer lag.
The openness directive applies to those agencies with more than $100 million in research and development expenditures. Agencies must develop plans to open data to the public within six months, and those plans will be vetted by the White House.
An industry group said the White House approach is a "reasonable, balanced" solution because it recognizes the value of publishers.
"The OSTP takes a fair path that would enhance access for the public, acknowledge differences among agencies and scientific disciplines and recognize the critical role publishers play in vetting, producing, establishing and preserving the integrity of scientific works," Tom Allen, chief executive of the Association of American Publishers, said in a statement.
But critics of the new policy said its value to the public and to scientists is undercut by the 12-month embargo.
"We are working on the cutting edge of the science. I want to read a new paper NOW, not in 1 year," Vittorio Saggiomo, a chemist at the University of Groningen in the Netherlands, wrote in an online chat about the announcement.
(Reporting By Mark Felsenthal; Editing by Paul Simao)