Johannesburg - Arms deal critic and losing bidder Richard Young is expected to testify on Wednesday at the Seriti Commission of Inquiry into the 1999 arms deal.
Young failed to appear at the inquiry on two previous occasions.
In February, the commission adjourned after Young asked it to postpone his appearance to March, in a letter he sent to the commission.
Young said his statement was not finalised and therefore he would not be in a position to present his evidence.
He also failed to attend and testify in July last year.
The commission was informed then that he had undergone an eye operation and was battling to read.
Young has reportedly raised concerns that the commission was not allowing allegations of fraud and corruption to be put to State witnesses, as these were meant to be dealt with only in phase two of the hearing.
He has accused the commission of being one-sided, in that it made no attempt to rigorously examine the evidence of government witnesses.
The commission, chaired by Judge Willie Seriti, was appointed by President Jacob Zuma in 2011 to hold public hearings into the controversial arms deal.
Last year, Zuma extended the commission's term until April 30, 2015, after which it is expected to issue a report within six months.
Sapa