Objective Comprehensive Behavioral Intervention for Tics (CBIT) is a first-line treatment of Tourette syndrome (TS). However, the brain mechanisms involved in CBIT are poorly understood. Enhanced frontomesial EEG coherence during a Go/NoGo task has been suggested as a mechanism involved in voluntary tic control. In the current study, we conducted a randomized controlled trial to assess whether EEG coherence during a Go/NoGo task was associated with CBIT outcome. Methods Thirty-two children with TS were randomly assigned to CBIT or to treatment-as-usual (TAU). Treatment outcome was assessed by a blinded evaluator with the Yale Global Tic Severity Scale (YGTSS) and the Clinical Global Impression – Improvement Scale (CGI-I). EEG was recorded during a Go/NoGo task at baseline and endpoint. EEG coherence was computed in the alpha frequency band between a priori selected channel pairs spanning the frontal and motor areas. Results Tic severity decreased significantly in the CBIT group. However, CBIT did not impact EEG coherence and baseline EEG coherence did not predict treatment outcome. Conclusions Although CBIT was superior to TAU on blinded clinical outcomes, EEG coherence during the Go/NoGo task was not associated with change in tic severity. Significance The brain processes involved in the inhibition of motor responses do not appear to be involved in CBIT.