Background: Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique tested in several diseases, including traumatic brain injury (TBI). Anodic and cathodic tDCS are typically used to increase and decrease excitability, respectively, and depending on mounting and stimulation parameters, tDCS can target different brain networks. This study will examine the immediate and late effects of tDCS on cognitive function, pain, functional independence, anxiety and depression, in-hospital complications and length of stay in subjects with severe TBI in the subacute phase. Methods: This is a randomized, two-arm, prospectively enrolled study with blinded allocation, raters, participants, and therapists blind, and intention-to-treat analysis. The study will consist of 30 subjects with severe TBI, who were discharged from the intensive care unit at least two weeks ago. Participants will be randomly allocated into an experimental group (i.e, tDCS 2mA active for 20 minutes) or a control group (i.e, tDCS sham for 20 minutes). Participants will receive sessions tDCS 5 times a week for 4 weeks, for a total of 20 sessions. Outcome measures will be collected by trained researchers at baseline (week 0), after 20 tDCS sessions, i.e at week 4 (week 4), 6 months later by telephone, and one year after treatment, also by phone. Discussion: The search for adjuvant therapies to improve TBI outcomes is challenging, mainly due to the heterogeneity, complexity and severity of the lesions. Thus, the results of this trial may result in an important advance for neurological rehabilitation. Trial registration: Brazilian Registry of Clinical Trials (ReBEC), RBR-37t4kc4. Registered prospectively on July 26rd , 2021