Anterior cingulate cortex has been functionally linked to the detection of outcomes that are worse than expected using both scalp electrophysiological [event-related potential (ERP)] and hemodynamic [functional MRI (fMRI)] responses. This study used a reward prediction violation design which acquired both ERP and fMRI data from the same participants in different sessions. Both the medial frontal negativity (MFN) ERP response and anterior cingulate cortex hemodynamic activity differentiated between reward delivery and expectation with the largest MFN and anterior cingulate cortex response when predicted rewards were not delivered. Inverse modeling placed the MFN source near the anterior cingulate cortex hemodynamic activation. The fMRI study also showed increased striatal response to rewards regardless of prediction indicating dissociation of neural processing of reward and reward expectation.