The Vatican is to open its archives to allow historians to access documents from 1922 to 1939.
Pope Pius XI oversaw the Vatican's relations with pre-war Germany
Documents from the pontificate of Pius XI will be made available, and could provide an insight into the Vatican's attitude towards the growth of Nazism.
New information about the Catholic church's views on the Spanish Civil War of the 1930s may also be unearthed.
Pius XI's successor, Pius XII, has long been accused of failing to help Jews during the Nazi genocide during WWII.
But the key records potentially contained in Pius XII's archive will remain closed, despite requests from rabbis and Jewish historians when current Pope Benedict XVI was elected.
Historians have clamoured for greater access to the Vatican's secret archives in an attempt to demystify the role of the church in the run-up to WWII.
Wealth of history
The archives contain records of all Papal decrees, encyclicals and Vatican diplomatic correspondence.
Records of individual papacies have been released at irregular intervals since the majority of the collection was opened in the 19th century.
In 2003, Pope John Paul II announced he would release papers detailing the Vatican's relationship with pre-WWII Germany.
Scholars are only allowed access to the collection, which is housed in the Vatican, under strict rules, including a ban on ballpoint pens.
The material to be released may include an encyclical that Pius XI commissioned to denounce racism and the violent nationalism of Germany, the Associated Press news agency reports.
The encyclical was titled "Humani Generis Unitas" or "The Unity of the Human Race", but Pius died before releasing it and it was never made public, AP adds.