Process for waterproofing a semimanufactured product (3) of footwear, gloves, clothing items and accessories, said semimanufactured product (3) having a three-dimensional conformation with at least one inner surface and one outer surface, characterized in that it comprises the following operative steps: arranging on a shaped support (1, 1a, 1b) the semimanufactured product (3) with at least one waterproofing sheath (4) shaped for entirely or partially cover the surfaces to be waterproofed of the semimanufactured product (3), at least one glue layer being applied between these surfaces and the waterproofing sheath (4); sealing the semimanufactured product (3) and/or the waterproofing sheath (4) for preventing the transfer of fluids from the outside between the sheath (4) and the shaped support (1, 1a, 1b); inserting the shaped support (1, 1a, 1b) provided with the semimanufactured product (3) and with the sheath (4) into an autoclave (7) for joining under pressure the sheath (4) to the semimanufactured product (3). The present invention also relates to a system that carries out said process, as well as the products obtained with said process or system.