Stuart Skinner, a bar manager at Hootananny in the Highland capital, was trying to light a bio-ethanol fire when he was engulfed in flames.
Colleagues rushed to wrap him in a fire blanket before rolling him on the floor in a desperate attempt to dowse the flames, it has been reported.
Church Street in the city centre was closed down by emergency services and the pub evacuated following the incident, around 5.20pm last night.
Duty bar manager Ruairidh Duncan witnessed the incident.
He told reporters: “We didn’t know who it was at first, it all happened so quickly and we could see this person on fire from head to foot.
“It was absolutely terrifying, we heard this explosion that sounded like a loud crack.”
A spokesman for Scottish Ambulance Service confirmed that a manin his 50s remained in a critical condition at Raigmore Hospital in Inverness.