<div class="htmlview paragraph">A new concept of combustion which is using the characteristic of plasma jet ignition, that is the plasma jet diffusive combustion is proposed. The constant volume vessel is used for the experiment, and methanol is charged in the cavity of plasma jet injector and the air at room temperature and atmospheric pressure is charged in the combustion chamber. The combustion characteristic is analyzed by measuring the combustion pressure and visualization of the combustion process. The plasma jet injector configuration and the ratio of methanol volume to cavity volume influence not only the plasma jet diffusive combustion process but also the maximum combustion pressure. In cases of small orifice diameter, the plasma jet diffusive combustion is not recognized, and the maximum combustion pressure increases as the orifice area becomes large. In the case of a little fuel is provided in the cavity, the enough methanol to initiate and to continue the diffusive combustion is not included in the methanol-air mixture jet and diffusive combustion does not occur. In the case where the most cavity is filled with methanol, the fuel mist is only ejected. In the case of appropriate methanol is supplied, the plasma jet diffusive combustion certainly occurs.</div>