Reactions of methylene chloride and methane in nitrogen bath were studied in tubular flow reactors of different diameters (4, 10, and 16 mm ID) over a temperature range of 750 to 1042°C at atmospheric pressure. The concentration ratio of methylene chloride/methane/nitrogen was kept constant at 1:4:10. Acetylene, ethylene, benzene, carbon, and hydrochloric acid were the major products for residence times of 0.08 to 2-5 sec at temperatures above 950°C. Stable chlorinated hydrocarbons detected at lower temperatures (<900°C) include chloromethane, trichloroethylene, and vinyl chloride. Significant wall effect was observed for surface to volume (S/V) ratios of greater than 10cm-1. The impact was unimportant at lower S/V (4, and 2.5cm-1’) ratios.