Officers were called to Station Approach following an allegation of assault shortly after 6.10pm on July 28.
The victim reported that two teenage boys had thrown a substance in her face, causing it to burn.
A 13-year-old boy was arrested on suspicion of using a corrosive substance with intent to cause grievous bodily harm.
He has been released on bail while police enquiries continue.
A spokesperson for Surrey Police said: “Were you in the area around Station Approach in Epsom on Monday, 28 July between 6pm and 6.10pm?
“Do you have any CCTV, dash cam or helmet cam footage that might have captured all or part of this incident?
“If you have any information that might assist our investigation, please contact us quoting PR/45250092021.”
