The remains were discovered at Freshwater Bay on the Isle of Wight. They were given in by a member of the public at the Boat House at about 11:00 GMT, Hampshire Constabulary said.
Initial analysis has confirmed it is a human hand which had been in the water for a significant amount of time, the force said.
It has been sent away for further analysis.
A human hand has been found by a dog after washing up on a beach.