The nine-month-old and his mother were ambushed as they were enjoying a picnic at Hanlon Park in Stones Corner about midday yesterday.
“It’s torture and I’m supposed to be his protector and I couldn’t protect him,” his mother told 9News.
A nurse who lives nearby heard the screams and came running.
“Took us straight up to her apartment and into the shower,” the mother said.
“The ambulance arrived pretty quickly.”
The mother’s friend chased the man, who fled and was unable to be found.
CCTV footage provided by police shows a man running away from the scene.
The boy’s parents said it was not known whether the burns would leave scars but the incident will leave a mark on their family.
“I’m just having flashbacks all the time about what happened,” the mother said.
“I don’t know who would think that is OK to harm a little, innocent baby.”
The boy will spend at least the next week in hospital, where he has already undergone one surgery with another planned later this week.
The man is described as aged 30 to 40, of a proportionate build, with tanned skin.
He was wearing a black hat, glasses, a shirt and shorts.
“Rest assured we’re doing everything we possibly can to find this person,” Detective Inspector Paul Dalton said.
Anybody with information or security footage of the area is urged to contact Crime Stoppers on 1800 333 000.