The effect of surface curvature on the development of a two-dimensional wall jet is investigated experimentally by direct comparison between a wall jet flowing around the convex surface of a circular cylinder, and its plane flow equivalent. Centrifugal force instabilities introduce rapid mixing of the curved wall jet with its surroundings, and cause significant increases in turbulence intensity and Reynolds shear stress in the jet. Large departures from self-preservation of the turbulence velocity field in the curved jet are observed, while the streamwise mean velocity profiles retain similar shapes for downstream development. Models for curvature effects on eddy viscosity are compared with experimentally measured values, and indicate that a simple correction for the effects of curvature is possible.