In this paper we derive local error estimates for radial basis function interpolation on the unit sphere S 2 ⊂ R 3 . More precisely, we consider radial basis function interpolation based on data on a (global or local) point set X ⊂ S 2 for functions in the Sobolev space H s (S 2 ) with norm · s , where s > 1. The zonal positive definite continuous kernel φ, which defines the radial basis function, is chosen such that its native space can be identified with H s (S 2 ). Under these assumptions we derive a local estimate for the uniform error on a spherical cap S(z; r ): the radial basis function interpolant X f of f ∈ H s (S 2 ) satisfies sup x∈S(z;r ) | f (x) − X f (x)| ≤ ch (s−1)/2 f s , where h = h X,S(z;r ) is the local mesh norm of the point set X with respect to the spherical cap S(z; r ). Our proof is intrinsic to the sphere, and makes use of the Videnskii inequality. A numerical test illustrates the theoretical result.2000 Mathematics subject classification: 41A05, 41A15, 41A25, 65D05, 65D07.