A thermosyphon is a gravity-assisted heat pipe used to improve the heat transfer in several applications. In this paper, a thermal analysis of a finned thermosyphon for heat exchanger applications was experimentally researched. The thermosyphon was manufactured from a copper tube the external diameter of 9.45 mm, the inner diameter of 7.75 mm, and a total length of 200 mm. The working fluid used was water with a filling ratio of 40% of the evaporator volume. The condenser was cooled by air forced convection, the adiabatic section was insulated with fiberglass and the evaporator was heated by an electrical resistor. Experimental tests were performed to a heat load from 5 up to 50W at vertical position (evaporator above condenser). As a result of the research, the thermosyphon operated satisfactorily to the tested position. Also, the finned thermosyphon obtained better thermal performance than the un-finned condenser, proving the effectiveness of the fin application.