Palestinian security officials named him as Dia al-Talahmeh and said he was shot dead by Israeli troops.
An Israeli army spokeswoman said he had been killed by a makeshift bomb he had been preparing to throw at the patrol but did not say whether or not the troops had opened fire.
The spokeswoman said the patrol had been deployed to clear stones blocking a road outside the flashpoint city of Hebron.
"The soldiers heard an explosion and during a search of the sector they found the body of a Palestinian killed by the explosive device he intended to throw at one of our vehicles," she said.
Tensions have been running high across the West Bank, including Israeli-annexed east Jerusalem, ahead of the Jewish Yom Kippur holiday which begins today.
Israel has deployed thousands of extra police in east Jerusalem and closed it off from the rest of the West Bank.