Police say shortly after 4 p.m. Wednesday, a woman was jogging along the trail from the Dundurn Stairs, when she heard someone call out to her.
The woman stopped and police say she was struck with an object, before allegedly getting sexually assaulted.
The woman was taken to hospital for minor injuries.
The suspect is described as white, six-feet tall with a thin build, short/shaved hair and grey facial hair. He was wearing a red T-shirt and a black baseball cap.
The Hamilton Police Service is encouraging any individuals and witnesses with further information to contact Det. John Tselepakis of the sexual assault unit at (905) 540-5545.