The video shows the suspect running shirtless down the sidewalk.
The attack happened around 10 p.m. on July 5 near the corner of West 47th Street and 6th Avenue.
Surveillance video showed the suspect run up behind the 57-year-old victim and throw the liquid on his back. The man then falls to the ground in pain.
Police said there were no words exchanged before the attack.
The victim was treated for second-degree burns.
Anyone with information about his attacker is asked to call the NYPD's Crime Stoppers hotline at 1-800-577-TIPS (8477), or for Spanish, 1-888-57-PISTA (74782). You can also submit a tip via their website or on Twitter, @NYPDTips. All calls are kept confidential.
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