Members of the Rail, Maritime and Transport union (RMT) at ScotRail will walk out on 10 October in a dispute over pay.
The union said its members had been offered a 5% pay rise, describing it as a real terms wage cut because of the soaring rate of inflation.
Rail unions are staging a series of strikes in early October over pay, jobs and conditions which will cripple services across the UK.
RMT general secretary Mick Lynch said: “ScotRail knows this offer is not good enough and needs to take into account the escalating cost-of-living crisis.
“Our members refuse to be made poorer and will exercise their industrial strength to let ScotRail know that they will not rest until they are paid what they deserve.”
Phil Campbell, ScotRail’s head of customer operations, said: “ScotRail has today been notified by the RMT that its members will hold ScotRail strike action on 10 October.
“This will have significant consequences for the service we are able to offer our customers.
“We will update our customers in the coming days on the full extent of the impact of industrial action.”
Separately, members of the GMB trade union in Scotland’s councils have accepted a pay offer after strike action by waste workers.
Waste workers in Edinburgh walked out at the height of the Edinburgh Festival Fringe, leaving rubbish to pile up on the street.
Staff in other council areas also downed tools, with the threat of non-teaching schools staff striking looming before Unite, Unison and GMB agreed to put a new deal to members.
First Minister Nicola Sturgeon personally intervened in the talks, calling a meeting that stretched on for more than eight hours, before council leaders made a new offer to staff the following day.
Some 81% of respondents voted in favour of the deal, GMB said.
The deal will provide a flat £1,900 increase for staff earning less than £39,000 per year, backdated to 1 April.
The union’s Scotland organiser Keir Greenaway said: “Our members have accepted the offer negotiated by unions and the First Minister by a clear majority.
“We are now calling on councils to ensure this consolidated increase is put into the pay and conditions of members as soon as possible, because the cost-of-living crisis hasn’t gone away.”
But the union leader said the end of the dispute should be a “point of reflection rather than relief” for politicians.
“Tens of thousands of low-paid workers were kept waiting months for movement on a decent pay offer in the grip of soaring inflation and eye-watering energy bills,“ read the statement.
“GMB is clear that after years of cuts to pay and services, this must be the start of the story in the fight for proper value of our key workers, because this period of intense economic pressure is going to last years and not months.”
Deputy First Minister John Swinney said: “I am very pleased that GMB Scotland members have accepted the pay offer for their members who work in local government in key roles across our communities.
“The Scottish Government is doing everything possible within the resources available to support the people of Scotland in the face of the cost-of-living crisis.
“I hope that members of the other local government unions will also vote to accept this pay deal, which ensures that those who need the most support get it.”
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