A Plasma Plant for the disposal of gaseous and liquid toxic waste containing halogen substances is working in laboratory scale at the "Istituto di Fisica del Plasma" (IFP) of Milan in the frame of the Strategic Project "Industrial Application of Plasma". The system has been completely designed and assembled at the IFP, using a commercial plasma torch with a maximum power of 80 kW d.c. The arc plasma process has all the requisites to operate in high temperature conditions and to minimize the molecular fragments recombination. The toxic waste is directly injected inside the electric arc produced by a torch. The dissociation of the toxic waste molecules occurs by impact with charge particles of the plasma. The dissociation of molecules in the plasma jet is continuously monitored by means of a spectroscopic system, while the recombination products, after the dissociation, are analyzed by a mass spectrometer working at high pressure. The produced effluents at a temperature of about 1200°C are subjected to a serie of successive treatments in order to cool the temperature, trap the dioxins and bond the halogens and to monitor the discharge fumes in the chimney. Design criteria and preliminary results obtained in the treatments of various types of organic molecules are exposed and discussed. Some specific diagnostic systems for the measure of the plasma parameters and the gas analysis in several sectors of the plants are described.