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.