About 100 litres of hydrochloric acid leaked from a container at the BMW Mini plant in Oxford.
A hazardous materials decontamination crew was sent to the Cowley site at about 02:00 BST.
One person taken to John Radcliffe Hospital after breathing in vapour has since been given the all clear.
Six fire crews attended the incident and put a cordon in place. The spillage took place in Building 50 on the site.
Two firefighters wearing breathing apparatus and gas tight suits removed other chemical containers.
A spokesperson for Mini Plant Oxford said the company will carry out an investigation and the Health & Safety Executive has been informed.
Oxfordshire County Council Fire and Rescue Service is continuing to secure the affected area, with a specialist chemical cleaning company removing the acid.
Incident commander Will McPhail said: "We have worked closely with colleagues from South Central Ambulance Service, Thames Valley Police and BMW emergency response staff to prevent the incident from escalating and maintain scene safety."
Article Source: BBC News