We studied the thermal decomposition properties of methylhydrazine (MH) which is used in the chemical vapor deposition (CVD) of titanium-nitride (TiN-CVD). The decomposition was carried out on the surfaces of silicon dioxide (SiO2) and titanium (Ti) at low pressures. The by-products were detected by the gas chromatography mass-spectrometry (GCMS), and surfaces were analyzed by electron spectroscopy for chemical analysis and Auger electron spectroscopy. MH decomposed on SiO2 surface above 400 degrees C producing methane (CH4), ammonia (NH3), and monomethylamine (MMA). Above 650 degrees C, CH4 and NH3 were predominantly generated instead of MH. The decomposition temperature on the Ti substrate was 200 degrees C and was even lower than the temperature on SiO2. As the substrate temperature increased, Ti was converted to TixNy aoproaching a stoichiometric TiN around 500 degrees C. As a result, MMA was observed around 400 degrees C. Due to the formation of TiN and its poor capability for donating electrons rather than Ti, the MH decomposition rate was reduced as temperature increased above 400 degrees C.