Patrick Harvie said the two parties had been “trying to finish off those last bits of discussion”, in an interview on the BBC’s The Sunday Show.
Asked about the widely mooted co-operation deal, Mr Harvie resisted going into any details, but said: “Everybody is very keen to know the outcome, I don’t think you have very long to wait.
“If we do agree something with the SNP it won’t be put into practice until our party members have had a vote … we’re trying to finish off those last bits of discussion.
“I hope very soon we’ll be able to publish something.
“The last session of the Scottish Parliament showed the Greens making an impact as an opposition party, pushing the SNP out of their comfort zone.
“If we can do that in a more coherent way over the long term of this five-year Parliament, we absolutely should be looking at how we can maximise that opportunity.”
An email seen last week said civil servants were considering a “New Zealand-style” co-operation deal between the SNP and Scottish Greens, which would be likely to see a Green MSP enter government.
The message, sent to members of the Scottish Greens on Friday, announces the postponement of a vote on the final deal until August 28 and pledges to provide the wording of an agreement to members by August 20.
The New Zealand model, which has seen Green Party MPs in that country take on ministerial portfolios while not being in an official coalition, is being considered by civil servants and Government lawyers, the email said – seeming to confirm one of the group’s eight MSPs will take on ministerial office.
Nicola Sturgeon announced talks had been launched on the creation of a co-operation agreement between the two parties after May’s election, which saw the SNP fall just one seat short of an overall majority.
The idea, according to the First Minister and the Greens, would see co-operation over specific issues, without a formal coalition deal.
Areas of co-operation are likely to include Scottish independence, which both parties support.