A small bomb exploded in an electrical junction box in front of the police academy in the Abbasiya district of Cairo on Sunday, Al-Ahram Arabic news website reported.
There were no reported injuries.
The use of home-made bombs and improvised explosive devices has been on the rise recently, taking centre stage after large-scale militant attacks against security forces decreased.
Egypt's army is battling an Islamist insurgency that has spiralled since the ouster of president Mohamed Morsi in July 2013.
Hundreds of security personnel have been killed in militant attacks nationwide, with the most ferocious assaults taking place in the restive Sinai Peninsula and Cairo.