Lawyers representing Tarek Loubani and John Greyson, along with a senior Canadian government official, were hoping to meet with a Cairo prosecutor to plead the case for freeing the men.
But the prosecutor failed to show up, and the lawyers were forced to leave the prison where the men are being held as a night-time curfew was approaching.
That left supporters of the men disappointed but vowing to continue fighting for their release.
"Despite our frustration, we are asking supporters of Tarek and John to wait for further news," said Justin Podur, a friend of both men who has been spearheading efforts to have them freed.
It was unclear whether another meeting with the prosecutor could be scheduled, or whether the detention order against them will be lifted.
But Podur remained hopeful that both men would be released soon.
"It's not devastating in the sense that I don't think this happened because there's some reason particular to John and Tarek," he said.
"Everybody who was to go before the prosecutor today was in the same situation."
Loubani, a doctor from London, Ont., and Greyson, who is a Toronto filmmaker and university professor, were detained Aug. 16 amid deadly riots in the Egyptian capital.
They were in Cairo trying to make their way to Gaza where Loubani was to teach emergency-room medicine and Greyson was considering producing a documentary.
Canadian foreign affairs officials have said it appeared the men were in the wrong place at the wrong time when they were detained.
But Egyptian prosecutors have accused them of "participating with members of the Muslim Brotherhood" in an attack on a police station.
Junior foreign affairs minister Lynne Yelich said she was disappointed Thursday's hearing did not take place, but vowed to continue efforts to ensure the detention is ended.
"We continue to work at the highest levels to confirm the specific charges against Dr. Loubani and Mr. Greyson," Yelich said in a statement.
"As we have not yet received confirmation of the charges, the government of Canada calls for their release."
Yelich said Canadian consular officials would continue meeting with the men as often as possible until they are let go.