Trial of Egypt's ex-leader Hosni Mubarak trial to open
Mr Mubarak has left the Sharm el-Sheikh hospital where he was being treated for a heart condition, en route to Cairo.
He is charged with corruption and ordering the killing of protesters - a charge that carries the death penalty.
His sons Alaa and Gamal, ex-Interior Minister Habib al-Adly and six former other officials will also face court.
Some 3,000 soldiers and police have been drafted in to maintain order at Cairo's police academy for the trial.
It was originally going to be held in a Cairo convention centre but the authorities moved the venue to a temporary courtroom set up inside the academy because of security concerns.
A cage for the defendants has been built and an estimated 600 people are expected to watch the proceedings.
Scepticism
Mr Mubarak, 83, has been under arrest at the hospital in the coastal resort town of Sharm el-Sheikh since April.
The former Egyptian leader resigned on 11 February, after 18 days of protests in Cairo's Tahrir Square, in which some 850 people were killed.
A cage has been built for the defendants in the courtroom
Mr Mubarak's lawyer insists the former president is seriously ill.
The BBC's Jon Leyne in Cairo says many Egyptians are sceptical about this and believe the military do not want to see the former president humiliated.
It is a very tense moment for Egypt, and if Mr Mubarak does not appear in court there could be serious confrontations on the streets, our correspondent adds.
"I don't think anyone has any illusions at the moment that the trial would actually be a real, fair trial," protester Nariman Yousseff told the BBC.
"We're all waiting to see what's going to happen, how they're going to get out of it, because it's been pretty clear and it's become even clearer in the last few days that... the Supreme Council of the Armed Forces, who are in charge at the moment, do not really have any intention of fulfilling the revolution's demands."
Over the past month there have been renewed sit-in protests in Tahrir Square by people angry with the slow pace of change in the country.
Among their demands to the military council in charge has been the call for speedier trial for former regime officials.
On Monday and Tuesday, police backed by army troops moved in to clear the last few protesters from square.
The former interior minister, who is going on trial with Mr Mubarak on Wednesday, was sentenced to 12 years in jail in May for money-laundering and profiteering.