The call for hazmat crews came in at about 3:30 p.m.
The business, located near Crockett Street, is called Flash Tank Services.
We're told the tank held toluene, a hydrocarbon associated with paint thinner
Authorities say it's not exactly clear how the man died since he was wearing a respirator at the time.
The Harris County Sheriff's Office is conducting an investigation. OSHA has been called to the scene as well.
The man's identity has not been released.
The company declined our request for a comment at this time.