A hand exoskeleton for assistance to a spherical motion of a carpo-metacarpal joint of a thumb of a user, said carpo-metacarpal joint having centre of rotation P and being arranged for allowing a relative motion of a metacarpal bone of said thumb with respect to a back of the hand of said user, said metacarpal bone defining a longitudinal direction δ , said hand exoskeleton comprising a kinematical chain comprising: - a first rotational joint engaged to said metacarpal bone and to a first connection link , said first rotational joint arranged, when said hand exoskeleton is worn, to provide a relative rotation α between said first connection link and said metacarpal bone about a rotation axis x coincident with said longitudinal direction δ ; - a third rotational joint engaged to said back of the hand and to a second connection link , said third rotational joint arranged, when said hand exoskeleton is worn, to provide a relative rotation γ between said second connection link and said back of the hand about a rotation axis z integral to said back of the hand ; - a second rotational joint engaged to said first connection link and to said second connection link , said second rotational joint arranged to provide a relative rotation β between said first connection link and said second connection link about a rotation axis y ; said hand exoskeleton comprising a frame , in use, integral to said back of the hand , said third rotational joint engaging with said back of the hand by means of said frame , said hand exoskeleton characterized in that said rotation axes x, y and z intersect in a centre of rotation O , in such a way that, when said hand exoskeleton is worn and said centre of rotation O coincides with said centre of rotation P , said hand exoskeleton allows a spherical motion of said metacarpal bone with respect to said back of the hand about said centre of rotation P . - a first rotational joint engaged to said metacarpal bone and to a first connection link , said first rotational joint arranged, when said hand exoskeleton is worn, to provide a relative rotation α between said first connection link and said metacarpal bone about a rotation axis x coincident with said longitudinal direction δ ; - a third rotational joint engaged to said back of the hand and to a second connection link , said third rotational joint arranged, when said hand exoskeleton is worn, to provide a relative rotation γ between said second connection link and said back of the hand about a rotation axis z integral to said back of the hand ; - a second rotational joint engaged to said first connection link and to said second connection link , said second rotational joint arranged to provide a relative rotation β between said first connection link and said second connection link about a rotation axis y ; said hand exoskeleton comprising a frame , in use, integral to said back of the hand , said third rotational joint engaging with said back of the hand by means of said frame , said hand exoskeleton characterized in that said rotation axes x, y and z intersect in a centre of rotation O , in such a way that, when said hand exoskeleton is worn and said centre of rotation O coincides with said centre of rotation P , said hand exoskeleton allows a spherical motion of said metacarpal bone with respect to said back of the hand about said centre of rotation P . <EOS>