Egypt's military announced on Thursday that it had killed Abu Duaa al-Ansari, whom it identified as the leader of the Sinai branch of DAESH.
The chief spokesman for the military, Brigadier General Mohammed Samir, said that a series of air strikes near el-Arish, the largest town in the Sinai Peninsula, had also killed 45 other DAESH terrorists.
However, there was no immediate confirmation from the DAESH-affiliated militant group Sinai Province.
The army did not say when the strikes took place.
"This successful operation confirms the pledges of the armed forces to avenge their martyrs and... pursue all the terrorist elements and leaders wherever they are found until Egypt and its great people enjoy security and stability," the military said.
Hundreds of soldiers and policemen have been killed in an insurgency since mid-2013, when then army chief Abdel Fattah al-Sisi ousted President Mohamed Morsi following mass protests.
Most of the violence has taken place in northern Sinai, where pro-DAESH militants are based.
The military has conducted several campaigns to crush the insurgents and cut off arms supplies, demolishing border villages and tunnels it says had been used to smuggle arms and fighters from the Gaza Strip.
Locals say the tunnels were used to smuggle consumer goods to Gaza to ease the consequences of the Israeli blockade.
In 2014 an Egyptian militant group called Ansar Bayt al-Maqdis pledged allegiance to DAESH, changing its name to Sinai Province.
In 2015 the group claimed to have beheaded a Croatian man who worked for French geoscience company CGG, after abducting him on a road running from the west of Cairo.
The group also claimed responsibility for destroying a Russian airliner carrying holidaymakers from an Egyptian resort last year with a bomb, killing all 224 people on board.
Later that year the Interior Ministry announced the killing of top DAESH operative Ashraf Ali Hassanein al-Gharabli, suspected of involvement in the abduction and murder of the Croatian and in the bombing of the Italian consulate.