A dog was found with her stomach and head covered in creosote and burned near the London Road cemetery in Smallford in between St Albans and Hatfield.
A passerby, who found the small female springer spaniel still alive, took her to a nearby vet but she died from her burns shortly afterwards.
The spaniel, who was liver and white, had been bred from and was around four years old.
She was found at lunchtime on Tuesday 20 November.
RSPCA inspector Kirsty Withnall said: “We would like any information you can give us that might lead to the identification of this dog’s owner.
“To be deliberately burnt like this is an unimaginably cruel thing to do to any animal.
“If you saw anything suspicious in that area or simply know someone who has lost a springer spaniel, please call our inspectorate appeal line on 0300 123 8018.”
If you would like to help the RSPCA, you can give £3 now by texting HELP to 78866 (text costs £3 + one standard network rate message).
Notes to editors
Pictures are available from the national press office on 0300 123 0244/0288