A woman and a two-year-old boy had anti-freeze thrown over them by a man in a Lidl supermarket car park in Gipton, Leeds.
The incident took place on Saturday evening, following a dispute between the 27-year-old female victim and two males in a black Toyota Yaris car.
West Yorkshire Police said one of the men got out of a black Toyota Yaris and threw liquid over the pair, before leaving the area.
Both victims were treated at the scene for skin irritation and the child was also checked over in hospital.
A cordon was put in place and the scene was washed down by a police team. Emergency services determined that the liquid was not corrosive.
One of the suspects is described as black, stocky, medium height and in his mid 30s with a shaven head.
- Police would like to speak to anyone who witnessed the incident on Oak Tree Walk, Gipton, or who saw the suspects leave the scene.