The images show the captive being held over the edge of a high-rise building by a group of masked militants as a crowd watch on from the ground.
He is then pushed off, falling 100ft on to the concrete below.
Videos it has released show masked militants dangling men over the precipices of buildings by their legs to drop them head-first or tossing them over the edge.
As of last December, at least 36 men in Syria and Iraq have been killed by ISIS militants on charges of sodomy, according to the New York-based "OutRight Action International".
ISIS group fighters sometimes torture suspected homosexuals to reveal their friends' names and search their laptops and mobile phones, Daily Mail reports.
Even among ISIS opponents, gays find little sympathy. Some in the public who might be shocked by other ISIS atrocities say killings of gays is justified.
Syrian rebel factions have killed or abused gays as well.
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