Mona will be asked about a controversial off-the-record meeting that Ngcuka allegedly called with a group of black editors a few months ago.
Ngcuka's accusers maintain that this meeting is an example of the chief prosecutor's alleged abuse of his official powers.
Mona, who reportedly attended the meeting, has lodged an official complaint about it with the Public Protector.
Commission secretary John Bacon said yesterday Mona's testimony would determine whether it would be necessary to also call other reported attendees.
These included Mondli Makhaya of the Mail & Guardian and Mathatha Tsedu, former editor of the Sunday Times.
Bacon said journalists Elias Maluleke of the City Press and Joe Thloloe of e-tv had been excused from testifying.
Other witnesses lined up for this week's hearings are representatives of the Department of Home Affairs and of the government pension fund.
The Home Affairs representative will be asked about Ngcuka's passport.
This is related to an allegation that the apartheid government lifted a travel restriction on him.
The pension fund official will be asked about Ngcuka's membership of the fund, apparently to determine whether he received any benefits as an alleged apartheid government spy. – Sapa.