More than 1,400 black cats are being cared for by Cats Protection and are waiting longer to be rehomed because people prefer to adopt different coloured felines.
Now the charity is holding its annual National Black Cat Day in the hope it will encourage more people to rehouse such cats.
Danielle Draper, manager at Cats Protection's National Cat Adoption Centre in Sussex, said: "People seem to be more taken with torties, tabbies and other colours - perhaps due to a perception that variety adds spice.
"Although it's lovely to see these cats finding their forever homes, it's sad to see black cats left waiting in the wings. They make up about 23% of all the cats in Cats Protection's care and each one waits around a week longer to be rehomed than the average cat."
The day of action takes place on October 25 and has already won support from model Lucy Pinder.
She said: "I was really surprised to hear that black cats take longer to find homes, it's such a shame. Black cats make just as good pets as the more colourful moggies and often have particularly striking and noble looks so I'd recommend adopting a black cat to anyone thinking of getting a cat."
The charity is also asking black cat owners to support its campaign online by uploading stories of their pet.
To adopt a black cat and join in the campaign visit www.cats.org.uk/black-cats or call the charity's helpline on 03000 121212.