The group said members of the public reported spotting the cat on the roof about four days before rescuers were contacted.
Thomas enlisted the help of he South Wales Fire & Rescue Service, which was able to use ladders to reach the stranded feline.
The cat was found to be microchipped and was returned to his owner.
"This was certainly a 'rocky' ride for this poor cat -- trapped on the roof by a boxing club for a number of days," Thomas said.
"Thankfully, the cat didn't take a dive -- as he was a great height from the ground and clearly needed help," she said.
"The RSPCA will never throw the towel in when helping animals. Fortunately, this rescue was an undisputed success and the cat was returned to his home," Thomas said.
