Introduction: Transcranial Direct Current Stimulation (tDCS) is a promising technique for Parkinson's Disease (PD). It is crucial to document adverse effects (AEs) and participants’ motivation for the therapy's success. The aim of this study is to characterize the perception of AEs caused by tDCS and establish the relationship between perceived effort and motivation in a treadmill gait training protocol in individuals with PD. Materials and Methods: The study was approved under CAAE:45459521.6.1001.5188. Fifteen individuals (3 females and 12 males) with PD, age (x̅ = 63.3 years), Hoehn & Yahr (x̅ = 2.23 points) were included. All of them underwent 12 treadmill intervention sessions for 20 min. tDCS (2 mA, impedance less than 28 kΩ) was applied over the Left Dorsolateral Prefrontal Cortex (L-DLPFC) during training. After each session, individuals were questioned about tDCS AEs, self-perception regarding these effects, and motivation to continue in the protocol. Perceived effort during training was assessed using the Borg scale. Data normality was analyzed by the Shapiro-Wilk test and correlation by the Spearman test. Results: Skin redness (96%) and tingling (84%) prevalence were observed. There was a strong positive correlation between motivation for the current session and motivation after the session (r = 0.89) and motivation in the last week and motivation after the session (r = 0.82), while perceived effort showed a moderate and inverse correlation with current motivation (r = –0.50). Conclusion: This study emphasized the importance of assessing the adverse effects (AEs) of tDCS in PD patients during gait training. Despite the prevalence of some AEs, the protocol demonstrated safety and tolerability. These findings are significant in the rehabilitation of PD patients, as they highlight relevance for treatment success.