The hydrogen detector for gas media comprises a waterproof membrane and a housing with a potential measuring unit inside, a ceramic sensing element made of solid electrolyte, the cavity of which contains a reference electrode, a porous platinum electrode, applied on the external layer of the ceramic sensing element, a sealed lead-in tightly fixed inside the housing above the ceramic sensing element, a potential measuring unit that passes through the central core of the sealed lead-in and the lower bushing, wherein the ceramic sensing element is designed as a cylinder interlinked with the bottom located in the lower part of the cylinder. The external cylindrical surface of the ceramic sensing element is tightly connected to the inner side surface of the housing. The standard electrode is located in the inner cavity of the ceramic sensing element. The external part of the bottom of the ceramic sensing element is covered with a layer of the porous platinum electrode. The end of the central core of the potential measuring unit is brought out to the standard electrode, thus the electrical contact is provided between the standard electrode and the lower part of the central core of the potential measuring unit. The lower bushing designed as a tube is connected to the lower part of the housing on the side of the ceramic sensing element. The lower end of the lower bushing has a bottom with a center hole with an attached selective membrane made of at least one tube. The lower free end of the selective membrane is tightly closed with a plug. The cavity limited by the inner surface of the lower bushing, the external part of the bottom of the ceramic sensing element and the inner surfaces of the selective membrane and the plug is made leak-tight by means of glass-ceramic sealant. The detector is equipped with an additional thermally-insulated heater that serves for heating and sustaining stable operating temperature on the sensing part of the operating element.