A catheter for ablating tissue is disclosed that has a self-centering multiray electrode assembly. The self-centering multiray electrode assembly may have a plurality of spines, each of which a preshaped, expanded configuration that curves to change an orientation of the spine from being directed towards the distal end of catheter body to being directed towards the proximal end of the catheter body. The ablation electrodes engage ostial tissue when a maximal outer diameter of the self-centering multiray electrode assembly is engaged with an inner diameter of a vessel. The compliance of each spine may vary along its length. When the self-centering multiray electrode assembly is engaged within a vessel, the ablation electrodes are brought into contact with tissue and may be used to form lesions in a circumferential path around the vessel.
