Manufacturing process of three-dimensional leather objects, comprising the following steps: - providing a piece of leather with a flesh side and a grain side; - providing a shape with the same shape as a three-dimensional object to be obtained; - positioning the flesh side of the piece of leather on the shape; - introducing the shape with the piece of leather inside a vacuum sack in such a way that the vacuum sack generates a membrane applied on the grain side of the piece of leather; and - applying rough vacuum in said vacuum sack in such a way that the flesh side of the piece of leather adheres on the shape; characterized in that said process comprises the following steps: - applying a hardener additive on the flesh side of the piece of leather; wherein said hardener additive is activated at an activation temperature of approximately 40°C-approximately 50°C; - drying of the hardener additive; - heating the vacuum sack with the shape and the piece of leather until the piece of leather reaches the activation temperature of the hardener additive; - applying vacuum progressively during the heating step, in such a way to progressively compress the piece of leather onto the shape until the desired shape is obtained; - cooling the vacuum sack with the shape and the piece of leather until the piece of leather reaches a temperature of approximately 25°C in vacuum conditions; - extracting the shape with the piece of leather from the vacuum sack; and - removing the piece of leather from the shape in such a way that the piece of leather has the shape of a three-dimensional object. - providing a piece of leather with a flesh side and a grain side; - providing a shape with the same shape as a three-dimensional object to be obtained; - positioning the flesh side of the piece of leather on the shape; - introducing the shape with the piece of leather inside a vacuum sack in such a way that the vacuum sack generates a membrane applied on the grain side of the piece of leather; and - applying rough vacuum in said vacuum sack in such a way that the flesh side of the piece of leather adheres on the shape; characterized in that said process comprises the following steps: - applying a hardener additive on the flesh side of the piece of leather; wherein said hardener additive is activated at an activation temperature of approximately 40°C-approximately 50°C; - drying of the hardener additive; - heating the vacuum sack with the shape and the piece of leather until the piece of leather reaches the activation temperature of the hardener additive; - applying vacuum progressively during the heating step, in such a way to progressively compress the piece of leather onto the shape until the desired shape is obtained; - cooling the vacuum sack with the shape and the piece of leather until the piece of leather reaches a temperature of approximately 25°C in vacuum conditions; - extracting the shape with the piece of leather from the vacuum sack; and - removing the piece of leather from the shape in such a way that the piece of leather has the shape of a three-dimensional object. - applying a hardener additive on the flesh side of the piece of leather; wherein said hardener additive is activated at an activation temperature of approximately 40°C-approximately 50°C; - drying of the hardener additive; - heating the vacuum sack with the shape and the piece of leather until the piece of leather reaches the activation temperature of the hardener additive; - applying vacuum progressively during the heating step, in such a way to progressively compress the piece of leather onto the shape until the desired shape is obtained; - cooling the vacuum sack with the shape and the piece of leather until the piece of leather reaches a temperature of approximately 25°C in vacuum conditions; - extracting the shape with the piece of leather from the vacuum sack; and - removing the piece of leather from the shape in such a way that the piece of leather has the shape of a three-dimensional object.