The Unite union is campaigning to defend Phil Tepper, a rep at the Fujitsu IT company in Manchester. He faces a charge of gross misconduct.
This could result in instant dismissal at his hearing, set for Friday of this week.
The charge arises from his work as a safety rep, investigating complaints of work-related stress raised by members.
If he is sacked it will set a dangerous precedent for the work of other reps.
Join the Defend Phil Tepper rally, 8am, this Friday 1 April, outside the front of Central Park, Northampton Road, Manchester, M40 5BP. Sign a petition in his defence at www.ourunion.org.uk