All five accused face potential jail time of up to eight years for obtaining and disclosing confidential papers “concerning the fundamental interests of the Vatican State”.
The unprecedented prosecution of journalists – who say they were only doing their job – is being pursued under punitive legislation introduced in 2013.
The law was rushed through a year after Pope Benedict XVI's butler leaked damaging information about Vatican in-fighting which plunged the Holy See into crisis and, it is widely believed, contributed to the pontiff's decision to retire.
Spanish priest Lucio Angel Vallejo Balda, Italian PR expert Francesca Chaouqui and a third Vatican official, Nicola Maio, are charged with criminal association in order to obtain the documents and then divulging them to the press.
Journalists Gianluigi Nuzzi and Emiliano Fittipaldi are accused of illegal disclosure and putting pressure on the Vatican officials, particularly Vallejo Balda, to obtain documents which they used as material for books depicting financial irregularities and uncontrolled spending in the Holy See.
The Vatican officials were all members of a now defunct special commission set up by Pope Francis to advise him on economic reform.
Nuzzi and Fittipaldi's books showed that, amongst other issues, charity money was spent on refurbishing the houses of powerful cardinals.
Nuzzi's book contains a transcript of secret recordings of Pope Francis vociferously complaining about the Vatican throwing money away through poor financial management.
No protection of sources
The Vatican has not denied the veracity of the recordings or the authenticity of the documents.
Instead, officials have framed the revelations as old news based on problems which Francis has already addressed through his reforms, a clampdown on profligacy and a clean-up of the Vatican bank.
Fittipaldi, who was questioned by Vatican prosecutors last week, admits he never expected to face criminal proceedings.
“Maybe I'm naive but I believed they would investigate those I denounced for criminal activity, not the person that revealed the crimes,” said the journalist, who writes for the weekly L'Espresso.
Unlike Italy, the Vatican has no law protecting journalists' ability to keep the sources of their stories secret.
“Two people have already been arrested and jailed as a consequence of this leak of documents and now the Vatican authorities are accusing two journalists who have simply done their job,” Nuzzi, a freelance journalist, said on Monday.
“Therefore I will continue to inform my readers, to spread the contents of my book and to defend my work from those who hope to shift the attention from an unprecedented investigation into the wrongdoings of some members of the (Vatican bureaucracy) Curia.”
Chaouqui was released shortly after her arrest and has since reportedly claimed that Vallejo Balda, who will come to court from a Vatican cell, was exclusively responsible for illicitly recording the pope.
The scandal has revived painful memories of the last time employees aired the Church's dirty laundry in public.
In 2012, Pope Benedict XVI's butler engineered a series of leaks that revealed fierce infighting at the top of the Church and allegations of serious fraud in the running of the city state.
He was sentenced to 18 months in prison, before being pardoned by the pope but banished from the Vatican forever.
Nuzzi played a central role in breaking that story and has said the Vatican's reaction this time around reflects the intolerant mindset of the inquisition – as the Church's often brutal persecution of perceived heretics was called from the 12th to the 19th Centuries.