Abstract: A hinge device for securing the seat and lid to a water-closet pan includes a first part with a first portion fixed in a position in the vertical plane of symmetry of the pan and a second portion, joined to the first portion. A second part is provided which is fixed to the lid with rear edges hinged to the second portion of the first part by two first pins of horizontal axis. The seat includes a rear end hinged to the second portion of the first part by two second pins of the horizontal axis, the second pins lie in a position lower and to the front of the first pins. Only one hinge device is used for securing the seat and lid to the pan. A third part of plate form is provided to be fixed to the seat and having its rear edge hinged to the second portion of the first part by a single pin of horizontal axis. The second part of plate form includes a single part which is hinged to the second portion of the first part by a single first pin.