Reactive oxygen species (ROS) are believed to play a major role in the proinflammatory, M1-polarized form of neuroinflammation. However, it has been difficult to assess the role of ROS and their role in neuroinflammation in animal models of disease because of the absence of probes capable of measuring their presence with the functional imaging technique positron emission tomography (PET). This study describes the synthesis and in vivo evaluation of [ 18 F]ROStrace, a radiotracer for imaging superoxide in vivo with PET, in an LPS model of neuroinflammation. [ 18 F]ROStrace was found to rapidly cross the blood-brain barrier (BBB) and was trapped in the brain of LPS-treated animals but not the control group. [ 18 F]ox-ROStrace, the oxidized form of [ 18 F]ROStrace, did not cross the BBB. These data suggest that [ 18 F]ROStrace is a suitable radiotracer for imaging superoxide levels in the central nervous system with PET.