Atmospheric-pressure microwave plasma (APMP) was generated in the liquid phase (LPAPMP) using carbon felt pieces impregnated with NaCl. The decomposition reaction of liquid toluene was examined as an application of LPAPMP. The reaction was divided into three periods: in the first period,faint spark discharges were observed in liquid toluene (LPSD) and toluene began to boil; in the second period, LPAPMP was generated and toluene was decomposed rapidly; in the final period, APMP was generated, but toluene had already been evaporated off.