Firefighters were called after a drum was spotted emitting steam at the side of a St Helens road.
Crews were called to Robins Lane, Sutton, shortly after 7.40am on Wednesday (March 12).
On arrival, they found a five-gallon drum in a gutter at the side of the road with steam coming from it.
A cordon was placed around the drum and firefighters wearing gas tight suits sent in to inspect it.
Firefighters also placed special mats over drains near the drum to prevent any of the substance from entering.
Specialist fire officers were called out and the substance was believed to be a strong acid mixture.
Station manager Tony Brown said: “Firefighters assisted in preventing the spill from spreading. We cordoned off the area to prevent any further contamination to the environment and to protect the community.
“We are now consulting with the Environmental Agency to look at neutralising the substance.”
Two fire appliances were sent to the scene along with an incident management team.