A force-wide crackdown on the supply of the drug known as M-Kat or Meow Meow led to police raids around the region today.
Eleven addresses, in locations including Banbury, Aylesbury and Chipping Norton were visited by police in the dawn operation.
More than 100 officers executed the warrants under The Misuse of Drugs Act, cash, cars and controlled drugs were seized.
Homes in Margaret Road, Banbury, Hailey Road, Chipping Norton and Hulbert End, Aylesbury were among those visited.
Seven men aged 36, 27, 37, 39, 38, 48 and 30, all from Oxford, have been arrested on various drugs offences and are currently in custody.
Investigating officer, Det Chief Insp Darran Hill of the Specialist Operations Unit, said: “Today’s arrests have been made as a result of a lengthy and complex investigation into conspiracy to supply significant quantities of controlled and dangerous drugs within our communities.
“Today we have arrested seven people and searched 11 addresses that have resulted in the seizure of large quantities of controlled drugs, money and assets. Those arrested are currently being interviewed at police stations in the Thames Valley Police area and we are working closely with the CPS with regard to the outcome of this activity.
“Our investigation is far from over and our action today demonstrates our absolute determination and commitment to tackle organised crime through arrest and seizure of criminal assets, and in doing so protecting our communities and vulnerable individuals within them from the harm that substances such as Mephedrone can cause.
“I realise that carrying out such warrants can be distressing for communities, so I thank the residents for their cooperation and patience while we carrying out our searches.
“I would appeal to anyone who may have information about the supply of drugs or crimes linked to drugs to come forward and contact Thames Valley Police Enquiry centre on 101.”
A cannabis hydroponics set up was also discovered at an address in Wilkins Road in Oxford.
If you don’t want to speak directly to the police you can contact Crimestoppers anonymously on 0800 555 111 or online at www.crimestoppers-uk.org.
No personal details are taken, information is not traced or recorded and you will not go to court.