Pyrolysis of methylene chloride-methane mixture (6.7% & 26.7%) in argon bath were studied over the temperature range of 1023-1323°K at atmospheric pressure, residence times ranging from 0.1 to 2 seconds, and the CH2Cl2:CH4:Ar of 6.7:26.7:66.6 molar percent, respectively. Heterogeneous (reactor wall) reactions were (bund to be insignificant in reactors of lower surface to volume ratios (larger diameter). Major products analyzed at temperatures below 1173°K include C2H4, C2H6, CH3Cl, C6H6, and HCl. Trace amounts (≤ 1%) of CCl4, C2H2Cl2, C2HCl3, C2Cl4were identified at lower reaction temperatures ( < 1123°K). An initial elementary reaction mechanism (74 step) was developed and shown to fit the data very well.