Investigation of liquid hydrocarbons cracking under microwave radiation in the presence of a sensitizer was made. A mixture of light hydrocarbons (saturated and unsaturated) was produced. The efficiency of n-hexane cracking was about 2.5x10(-7) mole hexane/J absorbed microwave energy. During the microwave cracking of n-hexane at atmospheric pressure the ethylene content among
the products obtained was over 44 % mol. Traces of water or hydroxyl-containing molecules were found to have a great effect on microwave cracking of n-hexane. A model for the describtion of microwave cracking of n-hexane - ethanol mixture, using the principle of steady-state concentrations for active particles, was proposed.