Dielectric-coated ablation electrode having a non-coated window with thermal sensors

A catheter for applying ablation energy to biological tissue having biological fluid flowing thereby includes a shaft having a distal-end region defining a tissue-contacting surface and a fluid-contacting surface. A plurality of band electrodes are positioned at the distal-end region of the shaft. A thermally conductive and non-electrically conductive surface covering, covers a portion of each of the band electrodes substantially coincident with the fluid-contacting surface. Each band electrode thereby has at least one masked portion substantially coincident with the fluid-contacting surface and at least one non-masked portion substantially coincident with the tissue-contacting surface. Ablation energy is transferred through the non-masked portion of the electrode. One or more thermal sensors are located in the non-masked portion of each of the band electrodes.