The incident happened just after 4.10am today (Thursday) which has caused a full closure of the A34 southbound.
Police, Highways Agency contractors and the Fire Service are currently at the scene dealing with the incident as they deal with a chemical leak before recovering the lorry. The chemical leak is not hazardous to the general public.
Motorists are advised to allow extra time for their journey as there are long delays in the area and follow the diversion route, the solid Black Triangle and use the M40, M25 and M3.
The carriageway is not expected to open until later this afternoon, but will fully reopen as soon as it is safe to do so.
The Highways Agency provides live traffic information via its website, local and national radio travel bulletins, electronic road signs and mobile platforms, such as the iPhone.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000.
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.