Leaders of the Unite union met with officials from the site's owners Ineos under the chairmanship of the conciliation service ACAS.
Union members at the oil refinery, and adjoining petrochemical plant, are due to stage a 48-hour strike from Sunday in a row over the treatment of unite convenor Stephen Deans.
He was suspended by the company following the dispute about the selection of a Labour candidate in Falkirk, where he is chairman of the constituency party.
He was later reinstated but faces an internal inquiry by the company.
Acas issued a brief statement saying the talks had adjourned and will reconvene tomorrow at 1pm.
Pat Rafferty, Unite's Scottish Secretary, said: "Ineos management effectively imposed an adjournment on today's mediation at 8pm by leaving the meeting - very much a case of last-in, first-out.
"We are very disappointed matters could not be progressed this evening particularly as we presented a number of proposals in a bid to resolve this dispute and we were prepared to work throughout the night if need be.
"At this point in time, it seems Ineos management are more concerned about heading back to Grangemouth to continue with the cold shutdown of the site rather than working with us here at Acas to keep the site open.
"Further talks are scheduled for tomorrow afternoon, but we are approaching them more in hope than any great expectation."
Ineos has warned that Grangemouth is losing £10million a month and will close by 2017 without fresh investment and reduced costs.