The M6 in Cheshire was closed in both directions between junction 19 and junction 20 due to the large vehicle fire, a spokesman for Cheshire Police said.
The spokesman said: "The incident involves a light goods vehicle carrying a number of propane gas cylinders which is well alight."
Six fire crews were sent to the scene after the fire was reported at about 2.40pm on Wednesday.
A statement on the North West Motorway Police Twitter account said the driver and passenger of the vehicle were not injured.
A spokesman for Cheshire Fire and Rescue Service said firefighters, wearing breathing apparatus, were using hose reel jets to fight the fire from a safe distance.
Highways England said the closure was causing delays of about an hour.
UPDATE: The northbound carriageway is now open, but the southbound remains closed