In her speech to the Scottish Labour conference in Perth, she will accuse the First Minister of a "betrayal of social justice" and of failing to produce a single redistributive policy in seven years of government.
Her comments closely echo UK Labour leader Ed Miliband's address to the party faithful yesterday, when he said Mr Salmond's claim to be a social democrat had been exposed as a sham, as the party mounted a concerted effort to reclaim the mantle of Scotland's progressive political force.
In another sign of Labour's shift to the left, Ian Davidson, veteran MP for Govan, publicly blamed the "complacency" of Tony Blair's New Labour era for the rise of the SNP. Speaking at a conference fringe meeting, he said it was Labour's fault the independence referendum was taking place.
Ms Lamont will today accuse the SNP of favouring the better-off when she addresses activists at Perth Concert Hall. In a reference to the long-running council tax freeze, she will say: "Those with the most getting more, those with the least getting less.
"That isn't just a betrayal of social justice, it is a betrayal of everything we believe Scotland stands for."
She will also condemn the SNP's refusal to propose a 50p top rate of tax for an independent Scotland - a rate Labour have promised to restore across the UK if the party wins next year's Westminster election - and accuse Mr Salmond of failing to "fight injustice".
She will say: "Look beyond the Saltire. Look beyond the plaid. Look at the Scotland the Nationalists are building and what they plan to build.
"We have a Nationalist government which refused to reverse Tory tax cuts for millionaires and a Nationalist government which votes against giving workers on government contracts the living wage.
"Forget talk of indy-lite, this Nationalist government is Osborne Max."
Yesterday Mr Miliband made similar claims during his brief 19-minute speech. Citing SNP plans to cut corporation tax by 3p and to maintain the top rate of income tax at 45p if Scotland becomes independent, he said: "Alex Salmond has been exposed."
He also highlighted Labour pledges - not matched by the Nationalists - to tax bankers' bonuses, freeze energy bills and end zero-hours contracts as evidence of his party's greater commitment to social justice.
He said:"The SNP talk about social justice but they can't build it - because they can't be narrow nationalists and serve social justice at the same time."
Earlier in the day Scottish Labour's deputy leader Anas Sarwar published a "red paper", Together We Can, setting out long-term commitments including a pledge to halve child poverty by 2021.
He insisted the document was not a response to the Scottish Government's independence White Paper but confirmed a summary version would be sent to every household in Scotland in the run-up to the referendum on September 18.
Labour's positioning comes as both sides in the referendum debate step up efforts to target voters in Scotland's less affluent areas. Polls suggest higher levels of pro-independence and undecided voters in working-class areas.
SNP Westminster leader Angus Robertson MP said: "Over one-quarter of Labour voters are already voting Yes in September. Ed Miliband can't even persuade his own members and supporters on the referendum. Instead of attacking the SNP he would do better trying to understand why Labour are still so far behind in the polls "