Tantawi, who is the de facto head of state since a popular uprising toppled Mubarak in February, is one of the highest profile witnesses called to testify at the former president’s trial.
He had been due to appear in court on September 11, but postponed due to last-minute engagements.
Mubarak has pleaded not guilty to charges of involvement in the killing of protesters and corruption.
His trial follows months of protests demanding justice for the roughly 850 people killed during the revolt that ended his regime.
The hearing, at a police academy on the outskirts of Cairo once named after Mubarak, is being held behind closed doors “for security reasons” at the orders Judge Ahmed Refaat
The first two hearings, which were aired live on television, showed the ailing 83-year-old Mubarak lying on a stretcher in a cage in the courtroom.