Fidel, an eight-year-old black cat, turns up at Deal library almost every day while his owners are at work.
He spends the day on his favourite blue chair, only leaving the building when he sees his owners arriving home.
Staff say they have never tried to encourage Fidel with food and even used to put him outside when he first began to visit them, but he always came back.
Heather Hilton, district manager for Deal Library, said: "Fidel certainly seems to like coming here and he's very popular with our customers.
"I think he's a bit of an art critic too because we sometimes see him examining the pictures on the gallery wall," she added.
A spokeswoman for Kent County Council which runs the library said Fidel was such a "dedicated customer" that he sometimes arrived before staff and could be found waiting at the front door.
Fidel is a rescue cat, whose owners chose him from a local sanctuary after he was found abandoned in a flat in Deal.
I want to go to Deal library!!!!!!!!!!!!!!