The victim, in her 30s, was pulled into a wooded area and raped by an unknown man.
She was walking on Abingdon Road at around 11:50pm when she was approached by an unknown man near to the junction with Gordon Woodward Way.
After the rape the offender, who is described as a tall white man of skinny build and aged in his 40s, left the scene. At the time he was wearing a dark-dark coloured jacket.
Senior investigating officer Detective Inspector James Mather, of Oxford CID, said: “We are in the very early stages of this investigation, and we currently have a scene-watch in place opposite the Travelodge on Abingdon Road at the junction with Gordon Woodward Way.
“I fully appreciate the concern that this will cause in the local community, and we are investigating this incident with the utmost priority.
“There will be an increased police presence in the area throughout the day, and I would urge anybody who has any information or concerns to please speak to one of our officers at the scene.
“I am also asking anybody who has any information relating to this incident, or believes that they witnessed anything that can assist this investigation to please contact Thames Valley Police on 101, quoting reference number 43200216757.
“I would also urge anybody who was driving in the area and has dash-cam in their vehicles to please look at this and contact police if it has captured anything that can help this investigation.
“If you do not wish to speak directly with police, you can call the independent charity Crimestoppers 100% anonymously on 0800 555 111.
“The victim is currently being supported by specially trained officers and will continue to be at the forefront of this investigation.
“A number of area searches and enquiries have already been conducted.
“I would like to assure the community that we will continue to thoroughly investigate this incident, and I would re-iterate if you have any concerns or information, please don’t hesitate to speak to officers.”