Police said the man whose body was discovered on a road in Mountain Ash was an 86-year-old pensioner.
An investigation was launched by officers after what they described as the "sudden and unexplained" death in the early hours of Tuesday morning.
A spokesman for South Wales Police said the elderly man was found by a member of the public at around 3.20am on Penrhiwceiber Road in Mountain Ash.
On Thursday, the spokesman said initial investigations found that the death is "not believed to be suspicious".
The man's family have been informed.
The road was closed for a time on Tuesday and a police cordon put in place so investigation work could be carried out.
