Abstract Body: Stroke is the leading cause of serious long-term disability in the United States. Stroke recovery is greatly varied since the long term effect is determined by the site and size of the initial lesion. Specifically, post stroke motor impairments occur due to damage to the corticospinal tract and maladaptive upregulation of the cortico-reticulospinal tract. Transcranial direct current stimulation (tDCS) may be an effective treatment for stroke rehabilitation. However, conventional tDCS is limited by spatial resolution to precisely target a specific brain region. To improve its spatial resolution, this study used targeted high-definition tDCS (HD-tDCS) navigated by paired-pulse transcranial magnetic stimulation. In a double-blind randomized crossover study, stroke participants (n=12) had three visits 1) anodal HD-tDCS stimulation of the arm region of the primary motor cortex (M1) to improve function of the corticospinal tract in the lesioned hemisphere, 2) cathodal stimulation of the arm region of the dorsal premotor (PM) cortex to inhibit maladaptive use of the cortico-reticulospinal tract in the contralesional hemisphere, and 3) sham. The effect was measured by quantitative electroencephalogram (qEEG) metrics delta alpha ratio (DAR) and delta theta alpha beta ratio (DTABR), calculated from a pre and post 3-minute EEG. Acute changes in brain activity of these power bands have been associated with the severity of motor impairment post stroke. The results demonstrate that anodal (p=0.026) and cathodal (p=0.0108) stimulation significantly decreased the DAR compared to the sham. The reducation of DAR value is associated with the improvement of Fugl-Meyer Upper Extremity score. However, there were no significant differences found in the DTABR. These results indicate that both anodal and cathodal HD-tDCS may improve brain function following stimulation. However, future work is required on the use of qEEG metrics and its use as a marker of stroke recovery. This work is important as qEEG could be used as a more objective method, compared to clinical assessments, to track stroke rehabilitation.