Rhubarb — Food safety facts
Do not feed · Cats · full breakdown on the linked food page
Leaves contain high levels of oxalates that can cause kidney failure; the stems are also risky in quantity. Keep rhubarb away from pets.
Short answer
No, rhubarb is toxic to cats and should be considered an emergency. Both the leaves and the stalks contain oxalates, which can lead to kidney failure and other serious health issues. Even a small amount can be dangerous. If your cat has ingested any part of a rhubarb plant, contact the ASPCA Animal Poison Control Center immediately at 888-426-4435 for guidance.