The synthesis of a varistor powder based on ZnO is carried out with the further fabrication of a device structure within the framework of the sol-gel method. To monitor the processes occurring in the sol, the method of Fourier-transform infrared spectroscopy is used. Studies of the surface structure of the material are carried out using scanning electron microscopy. The constructed current–voltage characteristic of the varistor structure is nonlinear with a nonlinearity coefficient of 2.36. The use of the sol-gel method for the manufacture of devices of this type makes it possible to obtain a grain size of 0.25 μm and achieve a reduction in the sintering temperature to 900°C.