When high and short-pulse voltage was applied with a high repetition frequency to tungsten electrodes placed in water containing ammonia and water containing 2-methyl-2-propanol, gas evolved vigorously from the plasma generated between the electrodes. The main gas evolved was H-2 in both aqueous solutions. Decomposition of ammonia provided N-2 in addition to H-2. In the decomposition of aqueous 2-methyl-2-propanol solution, CO, CO2, methane, ethane, ethylene, and acetylene were generated in addition to H-2. The "temperature" deduced by kinetic consideration using the yields of C-2 products (ethane, ethylene, and acetylene) formed by the recombination of two methyl radicals was calculated to be ca. 4200 K. (C) 2018 The Japan Society of Applied Physics