The primary objective of this study is to determine, in a healthcare setting, the effectiveness of actual tDCS in reducing pain compared with placebo tDCS. This is a multicenter randomized controlled trial with parallel groups (real tDCS vs. placebo) blinded to participants, assessors and tDCS providers. The real tDCS group will receive a daily 20-minute session of tDCS (current intensity = 2 mA), for 5 consecutive days, while the placebo tDCS group will receive an equivalent treatment, but the current will be stopped after the first 30 seconds. The study will take place in 5 rehabilitation clinics in 3 Quebec regions. One hundred and fifty (150) seniors aged 65 years or older with chronic (\> 6 months), moderate to severe musculoskeletal pain will be recruited (50 participants/region). Follow-ups will take place at 1 week and 3 months post-treatment. The primary dependent variable is pain intensity (numerical scale from 0 to 10). Secondary variables will be measured using standardized and validated questionnaires: 1) pain-related interferences (physical function, mood, quality of life) and 2) perception of post-TDCS changes. Neurophysiological measures (pain control pathways).