Foreign Affairs Minister Simon Coveney has sent a personal message of solidarity to Irishman Ibrahim Halawa as he marks four years in jail.
The 21-year-old was incarcerated after being detained during Muslim Brotherhood protests in Cairo in 2013. Hearings have been adjourned and delayed numerous times over the past four years.
The prosecution case ended last month.
Mr Coveney marked the jail-time anniversary by urging Mr Halawa to stay strong.
He said he wanted to reaffirm his determination and that of the Government to secure his release.
"I welcome the fact that, earlier this month, Ibrahim finally had his day in court and his opportunity to defend himself against the charges that he faces, and I note that the group trial in which he is a defendant seems finally to be drawing to an end," the minister said.
"I look forward to the conclusion of the judicial process, and to a resolution of this long-running and complex issue.
"I am sending a personal message to Ibrahim Halawa today expressing solidarity with him, encouraging him to stay strong and hopeful, and renewing the Government's promise to him that we will continue to do everything possible to ensure that he is able to return home as soon as possible."
Mr Halawa, the son of a prominent Muslim cleric in Dublin - Sheikh Hussein Halawa - was imprisoned after being detained in a mosque near Ramses Square in Cairo as the Muslim Brotherhood protested over the removal of elected president Mohamed Morsi in August 2013.
He has been tortured and gone on hunger strikes during his imprisonment.
Former taoiseach Enda Kenny wrote to Egyptian president Abdel Fattah el-Sisi pleading for Mr Halawa's release on humanitarian grounds.
Mr el-Sisi said he could be released, but only once the trial has run its course.
Somaia Halawa, one of Ibrahim's sisters, said: "Four years is too long for someone who is innocent.
"Four years is too much for our brother, the 17-year-old boy who has become a man locked away from the world, his family, friends. Four years of which Ibrahim has given of his body and his spirit to stay alive. When will Ibrahim be home?"