Twenty-six-year-old Yingying Zhang was about a month into a yearlong appointment at the central Illinois university when she disappeared June 9.
Campus police say surveillance video shows her entering a black Saturn Astra vehicle in Urbana that afternoon. Her friends told authorities she had gone out to sign a lease.
Authorities have labeled the case a kidnapping, but aren't ruling anything out. The FBI announced the reward Saturday.
Zhang was working in the university's Department of Natural Resources and Environmental Sciences, researching photosynthesis and crop productivity. University officials say Zhang's visiting scholar appointment runs through April 2018.
She is from Jianyang, China.