PurposeCerebral Palsy (CP) is the commonest cause of childhood motor disability. Transcranial direct current stimulation (tDCS) is a promising adjuvant therapy, but research targeting upper and lower limbs simultaneously is needed. We aimed to pilot tDCS with upper/lower limb motor training, estimate the potential effect on motor function, and investigate brain imaging correlates of function.Materials and methodsParticipants (10-16 years) with CP affecting upper and/or lower limbs were randomised (online software) to 10 sessions of active (n = 14) or sham (n = 13) tDCS combined with motor training. The primary outcomes were upper and lower limb function assessed at 1-week post-intervention using the Jebson Taylor hand function (JTT) and Timed Up and Go (TUG) tests. Secondary, imaging outcomes included baseline tractography, grey matter volume, and resting state connectivity.ResultsAdherence was good: 74% completed all intervention sessions, 100% completed the primary outcome assessment. There were no between-group differences (1-week post-intervention, intention-to-treat; group-by-time JTT: F(1,25)=1.189,p = 0.286, partial-eta-squared = 0.05; TUG: F(1,25)=1.605,p = 0.217, partial-eta-squared = 0.06). Imaging showed subtle associations between better JTT at baseline and higher grey matter volume (caudate nucleus) and stronger sensorimotor resting state connectivity.ConclusionsThe trial was well tolerated, but effect sizes were small. Larger studies are needed to further explore tDCS for CP.