A BOC worker at the Whyalla Steelworks died after a medical emergency at an oxygen plant overnight.
Emergency services were called to the BOC site at the steelworks on Thursday night to attend the medical emergency involving the worker.
"Sadly the employee passed away," the company said in a statement.
"BOC is profoundly saddened by the loss of our colleague and our deepest sympathies are with the employee's family and friends.
"We are providing support and assistance to our team based at Whyalla."
BOC is co-operating with emergency services and SafeWork South Australia has been notified about the incident.
Steelworks operator GFG Alliance confirmed SafeWork SA had been contacted and that police attended the site of the incident.
BOC is an Australian gas company which supplies gases, welding supplies and industrial equipment.