This study deals with the optimization of the location of a synthetic jet on the suction side of an airfoil to control stall. The optimal location is found by coupling a time-accurate flow solver with adaptive mesh refinement/coarsening techniques and an automatic optimization algorithm. The flow and jet are modeled by the unsteady Reynolds-averaged Navier-Stokes equations (URANSE) with a near-wall low-Reynolds number turbulence closure. An unstructured grid refinement/coarsening method is used to automatically generate meshes adapted to the presence of the synthetic jet at a prescribed location. An optimization algorithm modifies the location of the synthetic jet to determine the best actuator location to increase the time-averaged lift for high angles of attack. The proposed methodology is applied to optimize the location of a synthetic jet on the suction side of the NACA 0012 airfoil at a Reynolds number Re=2×106 and incidences of 18deg and 20deg⁠. Finally, a physical analysis of the influence of the synthetic jet location on the control efficiency is proposed to provide some guidelines for practical jet positioning.