Labour leader Ed Miliband is expected to put forward plans to outlaw the exploitative use of zero-hour contracts in his TUC speech.
Hundreds of thousands of workers are on the contracts which allow employers to hire staff with no guarantee of work.
Mr Miliband will tell the union organisation the contracts have been "terribly misused" in some cases.
He will say he would ban employers from insisting that workers be available when there is no guarantee of work.
The government has previously said it will decide this month whether to hold a formal consultation on possible changes to employment laws covering the contracts.
Under Labour's proposals, zero-hour contracts requiring people to work exclusively for one business without the guarantee of adequate hours in return would be outlawed.
And there would be action taken to prevent them being used for people working regular hours over a sustained period.
In his address, Mr Miliband will acknowledge that more flexible working has been one of the keys of keeping people in work despite the recession.
"We need flexibility. But we must stop flexibility being used as the excuse for exploitation," he will say.
"Exploitation which leaves workers carrying all of the burdens of unpredictable hours, irregular pay, no security for the future.
"And nowhere is that more true than when it comes to zero-hour contracts."
He will add that in some situations they are "useful", such as for doctors, supply teachers or young people who work in bars.
"But you and I know that zero hours contracts have been terribly misused. This kind of exploitation has to stop," he will say.
"We will support those businesses and workers that want to get on in life. But we will ban practices which lead to people being ground down."
'Confident and secure'
He will say that to a "recovery that works for all" will only come about when "working people feel confident and secure at work".
The Labour leader has asked Norman Pickavance, former director of human resources at supermarket Morrisons, to consult with businesses on how the changes could be implemented and whether the law would need to be changed to enforce them.
Labour had held a summit to discuss options for clamping down on zero-hour contracts last month.
Meanwhile, according to a survey of 5,000 Unite members, as many as 5.5 million people could be on the controversial arrangements.
The union said its research showed there was a "growing sub class" of insecure, low paid employees earning an average of £500 a month.