Police said a woman called to report finding the body in the 1400 block of B Street around 2:15 a.m.
The man is described as black and between 25 and 30 years old. Police said he may have been a transient, and that he appeared to have been dead for less than 24 hours.
Anyone with information about the death is asked to call Hayward police at (510) 293-7272 or (510) 293-7034.
