Process for waterproofing semimanufactured footwear, clothing items and accessories, said semimanufactured product having a three-dimensional conformation with at least one inner surface and one outer surface, which comprises the following operative steps: arranging the semimanufactured product onto a shaped support (14; 27, 28; 30, 31) with at least one waterproofing sheath (18) shaped for entirely or partially cover the surfaces to be waterproofed of the semimanufactured product, at least one glue layer being arranged between these surfaces and the waterproofing sheath (18); pressing between two deformable plates (2, 2') the semimanufactured product provided with the waterproofing sheath (18) and arranged on the shaped support (14; 27, 28; 30, 31). The present invention also relates to a machine that carries out said process, as well as the semimanufactured products obtained with said process or machine.