Caroline Lucas has been on the campaign trail, joining anti-fracking protesters and Scottish Green activists in Falkirk.
The party wants to see an outright ban on hydraulic fracturing which is used to recover shale gas from the ground.
The SNP advocates a moratorium on the practice in Scotland while further evidence into its environmental impact is gathered while Scottish Labour recently announced it would implement a ban.
Ms Lucas said: “I think fracking could well be a decisive issue for many people when they come to cast their vote, and when they look at it they will see the Greens have been opposed to fracking from the beginning.
“We haven’t got just a slightly mealy-mouthed moratorium, we haven’t got people who have just come to a ban late in the day.
“Right from the start, the Greens have been saying that we need to leave around 80 per cent of fossil fuels in the ground to have any chance of avoiding the worst of climate change.”
She added: “A moratorium pre-supposes that there is more evidence we are searching for to find out whether fracking is dangerous – our position is absolutely clear that to be going after yet more fossil fuel reserves at this time is just deeply irresponsible.”
Ms Lucas said the Greens’ stance on the issue could tempt SNP supporters who back a ban on fracking to give the party their regional list vote on Thursday.
She said: “I do think that we could be attracting SNP supporters to vote Green on the regional list vote. People have got the option now to elect politicians to make sure fracking doesn’t happen in Scotland.”
She added: “I think the exposure that the Greens got during the referendum campaign has really put us on the map and there is a real sense now that the Greens are a very viable option, and more and more people are looking to the Greens for some bold policies to shake up Holyrood.”
Elsewhere on the campaign trail, Labour leader Kezia Dugdale pledged to give the next generation the same opportunity to buy a house as her parents had.
She said “Scotland’s housing crisis” has forced people to turn to “rip-off rents” levied by private landlords.
Labour will build 60,000 affordable homes, including 45,000 for rent by councils, housing associations and co-operatives, cap rents and double support for people saving for a deposit, paid for by taxing higher earners.