The governor's call for a special session only affects the senate since the Illinois House already planned to meet that day in Springfield.
Quinn chose Chicago's City Club luncheon to make his proclamation on Monday.
"The liability in the public pension system goes up by $12.6 million every single day," said Quinn.
The governor repeated his theme of urgency to the business, civic and political leaders in the audience.
The state's long-term pension debt is around $85 billion, and paying the annual obligation to retirees is shortchanging education, health and public safety.
"Our state budget needs to have this kind of reform if we're going to have adequate money for our children, for our schools and the other things I just mentioned," Quinn said.
The Illinois House already planned to be in session on August 17 to decide whether to expel indicted State Representative Derrick Smith.
Many house members as well as senators are skeptical much could be accomplished in one day.
"Do I have my doubts? Without question. Like anything, it's a process," said Sen. Donne Trotter, (D) Chicago. "It didn't happen overnight. It's not going to be corrected overnight."
"I just don't think in a couple of hours on a Friday in the middle of August we're going to be able to accomplish the governor's goal," said Rep. Lou Lang, (D) Skokie.
"If they can negotiate a deal and ratify it on August 17th, I think it's possible," said Roosevelt University Professor Paul Green. "If they start on August 17th, it will be the longest day."
Earlier this summer, the governor and legislative leaders met but could not agree on how suburban and downstate school districts would begin paying the employer's share of pension contributions.
The governor opposes spending more time to study the issue.
"We cannot have paralysis by analysis. It's time for real action," said Quinn.
The August 17 special session in Springfield will follow Democrat and Republican political gatherings on the 15th and 16th, respectively, at the Illinois State Fair.
The governor wants citizens to pressure their lawmakers to get pension reform done. He says lawmakers should be held accountable in November if they don't do it before the election.