An improved electro surgical instrument is provided for cauterization and/or welding of tissue of varying impedances, thicknesses and vascularity especially in the performance of endoscopic procedures. The instrument compresses the tissue between one pole of a bipolar energy source located on one interfacing surface, and a second interfacing surface. A second pole is located on one of the two interfacing surfaces. In a preferred embodiment, the second pole is located on the same interfacing surface as the first pole and an insulator electrically isolates the two poles. A preferred application of the invention is in a cutting instrument wherein a hemostatic line is formed along a cut line using RF energy.