Officials received a complaint that a male subject approached two children near S. Military Rd. and Morris St. near the bike path.
Police say the man eventually exposed himself to the two children in Taylor Park.
The man is described as being a white male in his 50s, with short red/brown, graying hair.
Officials say the man was wearing a green shirt and some type of skirt or shorts that looked like a skirt.
Police also say he was riding a "Next" mountain bike.
Anyone with information regarding this incident is asked to contact the Fond du Lac Police Department at 920-906-5555.