Rail union RMT is balloting staff across First Great Western for industrial action over 'draconian dismissals' zero hour contracts and agency working.
The ballot – for both strike action and action short of a strike – will close on April 22.
RMT says staff are "extremely concerned over the company’s harsh dismissals and disciplinary procedures which have led to the unjust dismissal of two of our members".
The union also has "serious concerns regarding First Great Western’s proposed collective agreement on the use of agency and contract workers".
The union is demanding that the company "enter into meaningful negotiations around a collective agreement regarding the use of both agency and contract workers".
RMT also wants to see an end to the use of zero hour contracts.
Acting General Secretary Mick Cash said: “A company that values its staff offers decent pay and conditions, and that is all our members are asking for.
“First Great Western’s punitive dismissals and disciplinary procedure has to be changed so that in future our members can see proper justice in their workplace. In the meantime we want justice for our two members who have been unfairly dismissed.
“We want to see a collective agreement regarding the use of both agency and contract workers.
“We also want the company to end its use of Zero hour contracts, which we believe are exploitative and leave workers with no guarantee of what they will earn.
“The time has come for First Great Western to come to the negotiating table and resolve these long-standing issues. In the meantime RMT will both campaign and use industrial action to ensure workplace justice and decent pay and conditions for all First Great Western workers.”