Stephen R. Sparco, 57, of the Ashley Heights development in Wilmington, is charged with one count of possession of an incendiary device.
Police say the device was among a stockpile of weapons found Monday in the basement of Madeline's Italian Restaurant in Wilmington.
The restaurant's website lists Stephen Sparco as the third-generation owner of the family-run business, located at 6th and Dupont Streets.
Police and bomb experts responded to the restaurant Monday night, after they say a routine fire inspection turned up a number of suspicious items.
Police say those items included 36 firearms, over 20,000 rounds of ammunition, two functional homemade hand grenades and material to construct additional hand grenades.
Sparco was arrested, charged and released on $5,000 unsecured bail.
The investigation is continuing.
