The robbery happened around 12:45 a.m. Thursday at the 7-Eleven store at 2510 Kirkwood Highway.
Police say the men entered the store and the bandit in the Spider-Man mask pulled a gun on the clerk and demanded money as the other suspect, wearing a black mask, stood by.
The clerk turned over the cash and, police say, both suspects fled the store, heading east on Elizabeth Avenue.
The clerk was not injured.
Anyone with information is asked to call police at 302-834-2630 or Delaware Crime Stoppers at (800) TIP-3333.