Police were called at 11:118am on Tuesday, 13 April to reports of a corrosive substance attack at Bloomsbury Place, WCI.
Officers, London Ambulance Service and London Fire Brigade attended.
At the scene a male, aged 30s, had been sprayed in the face with a substance that had inflamed/irritated his eyes. He was taken by LAS to a central London hospital where he was found not to have suffered any lasting injuries and was discharged.
Detectives believe that the substance was sprayed during an attempt to rob the victim.
There have been no arrests.
Anyone who witnessed this incident or captured moving footage is asked to contact police on 101 or Tweet @MetCC quoting 2507/13APR.
To remain 100% anonymous call the independent charity Crimestoppers on 0800 555 111 or visit Crimestoppers_uk.org.