Stall is traditionally divided in three types of stall behaviour, these have been regarded as two dimensional and dominated by the airfoil shape. However one of these types of stall behaviour, trailing edge stall, has been shown in literature to be three dimensional by forming stall cells along the wing span. Stall cells are coherent flow structures consisting of localised patches of separated flow that are surrounded by attached flow. Most of the recent research is focused on determining the requirements for the formation of stall cells in terms of the angle of attack and the Reynolds number. Published results of these investigations use different airfoils and are thus not comparable. In this master thesis a NACA 0012 wing with plain flap has been used to assess the effect of the airfoil thickness and the camber on the stall cell formation criteria. The experimental results of the NACA 0012 wing have been compared to published results of a NACA 0015 wing to assess the effect of the airfoil thickness. The effect of the camber is simulated by deflecting the plain flap. Experimental results suggested that stall cell behaviour needs to be split into a low and a high Reynolds number regime, where the change in regime is airfoil dependent. Thick airfoils have been found to promote the formation of stall cells in the high Reynolds number regime but delay the formation of stall cells in the low Reynolds number regime. Adding camber to an airfoil was found to promote stall cell formation in both Reynolds number regimes. Further investigation of the formation criteria for stall cells indicated the importance of aerodynamic parameters such as the lift coefficient in determining stall cell formation criteria. Additionally the size and steadiness of the stall cells has been investigated by tracking characteristic vortical structures of stall cells. Although the angle of attack and Reynolds number have an effect on the stall cell size in spanwise direction, it was found that the minimum and maximum size of a stall cell are determined by the airfoil. Larger flap deflections were found to result in larger stall cells in spanwise direction. The unsteadiness of the stall cell spanwise position was observed to decrease with increasing angle of attack and decreasing Reynolds number.