Abstract Objectives We sought to evaluate whether porcine pulmonary vein (PV) isolation (PVI) can be produced by ablation using our novel radiofrequency (RF) thermal balloon catheter (RBC). Background It has been proposed that PVI can prevent focal atrial fibrillation (AF) originating in or close to the PV. Methods The RBC is composed of a 12F main shaft, a 4F inner tube and a balloon. Inside the balloon, there is a unipolar coil electrode with a thermocouple sensor mounted along the tube, the former to deliver RF energy (13.56 MHz) and the latter to monitor the temperature. After the presence of a PV potential was confirmed, the RBC was safely inserted into the left atrium (LA) by the trans-septal approach. Once the balloon was inflated and optimally wedged at the junction between the PV and LA, RF energy was applied for 5 min. Radiofrequency catheter ablation (RFA) was repeated up to three times, until elimination of the PV potential or dissociation between the LA and PV was observed. Finally, each heart was examined histologically. Results In 18 PVs that had PV potentials, PVI was performed, resulting in success in 15 (success rate 83%, 95% confidence interval [CI] 58.0% to 96.3%; failure rate 17%, 95% CI 3.7% to 42.0%). After successful PVI, the PV potentials completely disappeared and the histologic examination revealed circumferential, transmural necrosis around the PV trunks. No major complications, such as PV stenosis or macroscopic thrombosis, were observed. Conclusions The RBC was useful for PVI.