A man wearing a luminous pink polo top exposed himself to two women at a Bicester park.
At about 7.30pm yesterday a man in his thirties approached two women aged 18 and 21 in Bure Park Nature Reserve and exposed himself.
He then left using the main pathway through the reserve.
The man is described as wearing a luminous pink polo top which featured a white and black horizontal line across the chest.
He was also wearing tan-coloured shoes and was 5ft 6ins to 5ft 8ins tall, with brown receding hair and stubble.
Investigating officer PC Nickie Harrison said: "Although it is unlikely that any members of the public would have witnessed the incident itself, they may have seen the man walking towards or away from the location and may be able to identify him, or provide details of where he went after he left the wooded area.
"There are believed to have been a number of members of the public walking dogs in the reserve at the time of the offence and the hope is that someone will recall seeing the man in his distinctive clothing."
Anyone with information should contact PC Harrison on 101.