Powerhouse electrical stores across the country closed today and workers were sent home after being told the firm was going into administration.
The union Usdaw, which represents workers at the company, said staff were "devastated" after hearing they would be made redundant.
Powerhouse has more than 50 stores and employs around 800 workers, with a head office based in Bicester, Oxfordshire.
The stores are owned by the New Zealand-based PRG Group, which said earlier this year that Powerhouse was facing tough market conditions, with less than budgeted sales growth, which was expected to result in a moderate loss for the last financial year.
PRG bought Powerhouse from administrators in 2003.
A spokesman for Usdaw said staff turned up for work this morning but were sent home with redundancy forms.
"Our members have worked miracles in keeping this company afloat in a very competitive sector.
"They are devastated at being told to go home because they now face an uncertain future. We will work closely to ensure they get the redundancy they are entitled to and will work with the administrator to ensure that terms and conditions are respected.
"This is obviously a very difficult time for our members."Reuse content