A Green government would offer free social care for the elderly in a bid to make Britain a more "decent, humane and caring" country, Natalie Bennett has promised.
Caroline Lucas, the party's only MP, introduced the Australian-born politician at the party's spring conference in Liverpool.
Lucas praised the former journalist's leadership after the Green's membership numbers hit a record high of more than 55,000 in March.
Bennett, who received a standing ovation, revealed that free social care for all over-65s would be in the Greens' general election manifesto, which is expected to be released at the end of March.
"Free healthcare is the very cornerstone of our NHS. Whether you are rich or poor you have the right to the best that is available. That's something the Green Party will restore – and extend," she declared.
"We believe that to be a decent, humane, caring society, social care must be free."
Bennett explained that the policy would be funded by a wealth tax, increased levies on those earning more than £100,000 ($150,700, €138,772) a year and a so called "Robin Hood" tax, which would levy some corporate financial transactions.
She also told the attendees that they could "change the face of Britain" at the general election.
"Your vote can change the face of Britain. It can end the failed austerity experiment; end the spiteful blaming of the poor, the sick, and the vulnerable for the mistakes of the wealthy," Bennett said.
"This election can be a turning point in history. The moment where we can deliver a better Britain, a Britain which works for its people. A Britain which cares.
"Vote for what you believe in, vote for the policies of hope not fear, vote for policies that work for the common good not just the few, and Britain could be a very different country on the 8th of May.
"We, the Green Party, can be the agents of change. Real Change. It is time for Green Politics – the politics of the future."
The comments come after Bennett suffered a "car crash" radio interview on her party's housing policy.
But the setback has not been reflected in the opinion polls as the most recent survey from YouGov put the Greens on 8%.
The data puts the party above their 1% share of the vote in 2010 and ahead of the Liberal Democrats who are on 6%.