A pensioner needed hospital treatment after being sprayed in the face during a burglary.
The 80-year-old victim had answered his door in Brasslands Drive, Portslade to a woman posing as an estate agent.
She asked him if he was thinking about putting his house on the market and then sprayed a substance into his face.
While he ws distracted, two men came in and searched the house before leaving.
The man was taken to the Royal Sussex County Hospital in Brighton for minor injuries following the incident, which happened at about 7.10pm on Monday.
Detective Constable Vicky Bailey said: "We are supporting this elderly man who was shaken by the incident, and are keen to trace who is responsible."
The woman was described as white, well spoken, aged 28 or 29, between 5ft 7in and 5ft 8in and with straight dark shoulder length hair.
She was wearing smart dark clothing.
The two men were both white, aged between 30 and 40 and between 5ft 7in and 5ft 9in and wearing white t-shirts.
One had a v shaped tattoo on his right arm.
Any witness or anyone with information is asked to call 101 or email firstname.lastname@example.org serial 0072 of 10/6.