A catheter for the ablation of tissues comprising: - a telescopic tubular body in turn comprising an external tubular body and an internal tubular body concentric with each other, and a rod-like guiding element at least partly housed in the internal tubular body with at least one free end protruding from the internal tubular body in correspondence with a distal end of the telescopic body; - a positioning head (2,2",2"',2°,2*,2^) and an ablation head in correspondence with the distal end of the telescopic body, the positioning head (2,2",2'",2°,2*,2^) being situated in the proximity of the free end of the rod-like guide, and the ablation head in the proximity of the positioning head (2,2",2"',2°,2*,2^), in a remote position with respect to the free end; - a control handpiece at a proximal end of the telescopic body coupled with the guiding element, the ablation head, the positioning head (2,2",2"',2°,2*,2^) and the telescopic tubular body; wherein the ablation head comprises at least two ablation elements or petals that can be moved from a rest position in which they are housed in the external tubular body and an operating position in which they protrude from the external tubular body like a petal; each of the ablation elements or petals comprises: - a continuous ablation electrode which extends without interruption over a circumferential peripheral portion of each petal, substantially along an arc of circumference having a longitudinal axis of the rod-like guiding element as its centre; - two side portions of the petal, each connected to an end of the ablation electrode, in correspondence with a curved section, each ablation petal being separate and distinct from another ablation petal of the ablation head, all the ablation petals of the ablation head being separately connected to a distinct electric energy generator to cause a radiofrequency ablation in a powered ablation electrode condition, characterized in that the side portions and the ablation electrode are integral with each other, formed by means of the same folded metallic conductor, and wherein each ablation petal is produced with a single Nitinol wire having a circular section with a diameter D, and, as L is the linear length of the ablation electrode, there is the following ratio D/L ranging from 0.015 to 0.025. - a telescopic tubular body in turn comprising an external tubular body and an internal tubular body concentric with each other, and a rod-like guiding element at least partly housed in the internal tubular body with at least one free end protruding from the internal tubular body in correspondence with a distal end of the telescopic body; - a positioning head (2,2",2"',2°,2*,2^) and an ablation head in correspondence with the distal end of the telescopic body, the positioning head (2,2",2'",2°,2*,2^) being situated in the proximity of the free end of the rod-like guide, and the ablation head in the proximity of the positioning head (2,2",2"',2°,2*,2^), in a remote position with respect to the free end; - a control handpiece at a proximal end of the telescopic body coupled with the guiding element, the ablation head, the positioning head (2,2",2"',2°,2*,2^) and the telescopic tubular body; - a continuous ablation electrode which extends without interruption over a circumferential peripheral portion of each petal, substantially along an arc of circumference having a longitudinal axis of the rod-like guiding element as its centre; - two side portions of the petal, each connected to an end of the ablation electrode, in correspondence with a curved section,