Cleaners working on East Coast trains are to go on strike on Friday and Saturday in a pay dispute.
RMT members who work for cleaning company ISS on routes that serve Doncaster are unhappy they have not had a pay rise since 2011.
It is the latest strike action taken by union members in the ongoing dispute.
RMT acting general secretary Mick Cash said: “It is outrageous that ISS are refusing to take the matter of fair pay increases and improvements to terms and conditions seriously. To have had no pay rise since 2011 is a disgrace while this wealthy global company makes huge profits on the back of pure exploitation of the workforce.
“The ball is now in ISS’ court as RMT’s campaign continues.”
The RMT says it plans to hold picket lines on stations.