A protest will be held outside the Department of Foreign Affairs later, demanding the Government intervene in the case of Ibrahim Halawa.
The Dublin teenager has been imprisoned in Egypt since August 2013, after being arrested during political unrest in Cairo.
The 19-year-old's trial is due to begin tomorrow, however, it has already been postponed four times.
His family and supporters will hold a demonstration in Dublin at 2pm this afternoon, calling for the Government to demand his release.
Ibrahim's sister Somaia says the prison he is in is very dangerous.
She said: "I don't know what's going to happen on Sunday, it might be postponed, he might not be moved back to the same prison where he was with Peter Gresty.
"He could stay in that prison which is known as one of the worst prisons in Egypt, there have been a few death cases from torturing and beatings and people were electrocuted."