Arriva Trains Wales drivers' 24-hour strike in January
Arriva Trains Wales drivers will strike for 24 hours as part of a dispute over pay and conditions.
Members of the Aslef union will walk out on 4 January, the day many return to work after the Christmas break.
Union members backed strikes by 4-1 in a ballot, with a turnout of 80% and Aslef accused the company on reneging on a deal aimed at resolving the row.
Arriva said it was disappointed with the "unnecessary threat" of disruption.
Union members have also said they will refuse to work overtime from 28 December.
Gareth Thomas, human resources director at Arriva Trains Wales (ATW), said: "We are disappointed that train driver union members have rejected the current offer of increased pay and improved terms and conditions by supporting a ballot for industrial action.
"ATW management will do all it can to avert this unnecessary threat of imposed disruption to our customers and we are continuing an open and constructive dialogue with union representatives."
The news comes after a planned strike was called off in November.