Abstract. Let the space R n be endowed with a Minkowski structure M (that is, M : R n → [0, +∞) is the gauge function of a compact convex set having the origin as an interior point, and with boundary of class C 2 ), and let; y ∈ ∂Ω} be the Minkowski distance of a point x ∈ Ω from the boundary of Ω. We prove that a suitable extension of d Ω to R n (which plays the rôle of a signed Minkowski distance to ∂Ω) is of class C 2 in a tubular neighborhood of ∂Ω, and that d Ω is of class C 2 outside the cut locus of ∂Ω (that is, the closure of the set of points of nondifferentiability of d Ω in Ω). In addition, we prove that the cut locus of ∂Ω has Lebesgue measure zero, and that Ω can be decomposed, up to this set of vanishing measure, into geodesics starting from ∂Ω and going into Ω along the normal direction (with respect to the Minkowski distance). We compute explicitly the Jacobian determinant of the change of variables that associates to every point x ∈ Ω outside the cut locus the pair (p(x), d Ω (x)), where p(x) denotes the (unique) projection of x on ∂Ω, and we apply these techniques to the analysis of PDEs of Monge-Kantorovich type arising from problems in optimal transportation theory and shape optimization.