Schizophrenia is characterized by diverse symptoms ranging from delusional beliefs and hallucinations to cognitive disorganization. Cognitive disorganization encompasses different cognitive domains like executive functioning or memory and, in turn, hinders remediation processes and interferes with daily life. Due to this relevance, the aim of our study was to quantify the cognitive deficits in patients suffering from schizophrenia (SZP) and link them to potential changes in the frontal midline theta power in the electroencephalogram (EEG), an electrophysiological index related to initiating executive control. Thirty-two SZP and thirty-two matched healthy controls (HC) performed a Go/NoGo task assessing executive functioning, while EEG was recorded. Additionally, subjective cognitive complaints (CFQ, PDQ-5) and clinical parameters (PANSS, ESI) were collected. Preliminary results indicated that SZP compared to HC showed a lower theta power level irrespective of condition and lower evoked theta power increases and lower total percentage changes in the NoGo condition. Besides, SZP reported more subjective complaints and showed worse Go/NoGo performances than HC. Considering the SZP group, evoked theta increases were associated with faster Go reactions and less subjective delusional perceptions, and better Go/NoGo performances were related to less psychopathological symptoms. These results indicate that theta power changes, especially evoked parts, serve as a marker of abnormal oscillatory changes in SZP. Linking these electrophysiological findings to the behavioral data, HC seems to recruit executive control resources more efficiently than SZP. These results could be explained within the dysconnectivity hypothesis of schizophrenia and underline the relevance of neural oscillations for an intact neurobiological network communication.