Managers at Torbay Hospital are being accused of "insensitivity" after offering staff a Kit Kat each for winning a prestigious award.
The hospital was named acute healthcare organisation of the year in 2011 and about 20 of the hospital's staff celebrated at the awards in London.
The GMB union said giving the 4,000 workers a biscuit "looks a bit cheap".
Chief executive of Torbay Hospital Paula Vasco-Knight apologised to staff who were offended.
South Devon Healthcare NHS Foundation Trust, which runs Torbay Hospital, was recognised in the Health Service Journal awards for "best innovation, ideas and dedication".
Paul Raybould, from the GMB, said he had received about 30 complaints.
He said: "Management got a slap-up meal and we got only a 60p Kit Kat.
"They feel they are worth more than that."
He added: "It's a sign of management not thinking outside the box.
"They have just made themselves a laughing stock."
The vouchers were sent out in the last round of payslips to the hospital's staff.
Ms Vasco-Knight said the gift had been "misinterpreted" and she had received hundreds of emails from staff thanking her.
She said: "It's a way of thanking everyone - lots of 'thank yous' to show that we really appreciate staff.
"I apologise to staff who felt insulted."
She said no NHS money had been spent on the gifts which were paid for from donations to the hospital.
"I will think of other ways of thanking staff," said Ms Vasco-Knight.
The hospital had also held a prize draw for members of staff with prizes from sponsors including a spa experience and a weekend away.
A hospital spokesman said that money for the awards ceremony had also come from donations.
"It is not money that would be used for patient care," he said.
He added that staff at the awards represented all sections of personnel, not just management.
Kit Kats are the UK's best selling confectionery brand, with about £170m of sales a year.
About 13 billion of the snacks are sold worldwide every year.
In a statement the Trust said: "This was simply one light-hearted gesture as part of a whole programme of celebration and thanks to our staff for winning this award.
"We will not stop saying thank you to our staff.
"They are what makes this organisation successful and we are proud of what they have achieved for Torbay Hospital and for our patients."