The British Hen Welfare Trust said 240 of the birds were in need of new homes in Wrexham.
The trust said the birds had spent the last 18 months laying eggs for supermarkets but their ability to lay had slowed down.
It said they were healthy and "will soon become much-loved pets".
The trust will hold a rehoming day on Sunday but said it could not save the hens if they did not have homes to go to.
Gaynor Davies, the charity's head of operations, said: "There is no better feeling than watching these girls flourish after they emerge from the commercial system.
"With a bit of TLC they become incredibly tame, and they're often described as cats and dogs with feathers."

It comes after Swansea City FC's American owners revealed they are in talks with the council over increasing capacity at the ground.
The Swans want to add 12,000 seats but shelved expansion plans in December when talks to buy the ground from the authority stalled.
Since then, the club has been taken over by American investors.
Council leader Rob Stewart said: "We're pleased they reached a deal to buy the club," he said. "We want the club to go from strength to strength.
"The offer is still there and we're still open to the option of them procuring the stadium or going for a commercial deal with them expanding the stadium.
"We would be interested to see what the the American investors prefer."
The 21,000-capacity ground, which Swansea share with Ospreys rugby region, is the second smallest in the Premier League behind Bournemouth's Vitality Stadium.
Swansea have averaged crowds of about 20,500 in their last five Premier League seasons.
The club initially wants to increase capacity to 33,000 but the ultimate vision is to expand the stadium to 40,000 seats.
Last month, Swansea chairman Huw Jenkins said the club "has to make sure the council is on board" with the plans.
But Mr Stewart said the council had not recently commented on the proposals in order to allow the takeover by Jason Levien and Steve Kaplan to be completed.

The memorial, with the names of 27 local people, has been unveiled at the Unite building in Islington.
The city's office block has been called Jack Jones in honour of the ardent trade unionist from Garston who was badly injured in the conflict.
Unite's regional secretary Paul Finegan said: "We feel very privileged."
There were approximately 180 men and women who left the safety of Merseyside to defend the Spanish government against the might of General Francisco Franco's nationalist rebels between 1936 and 1939.
Jack Jones survived the war and became the leader of the Transport and General Workers' Union. He was heavily involved with the unions until he died aged 96 in April last year.
Local historian, Danny Payne, said that although there were 27 names on the plaque, after further research it is believed that 30 people from Merseyside died fighting.
They had to travel there in secret, after the UK government declared it illegal to fight in Spain as it tried to appease Hitler's huge fascist force in the lead up to the Second World War.
In total, 2,500 from across the British Isles fought in the Spanish Civil War and 500 did not survive.
Mr Finegan said: "The plaque used to be on the wall of the unemployed and trade union centre in Hardman Street, but since it closed years ago, it has been sent from place to place across the city.
"Now it's good that it has a permanent home here, it all seems to fit together well - a newly refurbished building called Jack Jones and a memorial dedicated to those who lost their lives in the same war he fought."
The civil war ended after WWII had started. More than 300,000 people died and the Republicans were persecuted by the victorious nationalist parties.
Mr Payne added: "It was an horrific war, Franco's uprising was supported by the Hitler and Mussolini regimes so he was furnished with arms.
"The Republic was short of weapons and medical supplies and it was basically strangled by the might of Franco."
Hundreds of ex-commercial hens considered too slow at laying eggs face slaughter unless they can be rehomed in north Wales, a charity has said.
[NEXT_CONCEPT]
Swansea council's leader is optimistic progress can be made during talks about expanding the Liberty Stadium.
[NEXT_CONCEPT]
A plaque with the names of those from Merseyside who lost their lives fighting in the Spanish Civil War has found a permanent home in Liverpool.