%0 Journal Article %T Regularity of $C^1$ surfaces with prescribed mean curvature in three-dimensional contact sub-Riemannian manifolds %A Matteo Galli %A Manuel Ritor¨¦ %J Mathematics %D 2015 %I arXiv %X In this paper we consider surfaces of class $C^1$ with continuous prescribed mean curvature in a three-dimensional contact sub-Riemannian manifold and prove that their characteristic curves are of class $C^2$. This regularity result also holds for critical points of the sub-Riemannian perimeter under a volume constraint. All results are valid in the first Heisenberg group $\mathbb{H}^1$. %U http://arxiv.org/abs/1501.07246v3