Analytical techniques using derivative thermogravimetry (DTG) and thermogravimetry analysis (TGA) were developed to estimate kinetic parameters for complex decomposition reactions of a heterogeneous substance like scrap tire rubbers. Two methods using non-isothermal techniques were proposed : (1) subtraction method and (2) method utilizing peak properties in a DTG curve. The former method is a reliable tool to determine the kinetic parameters of decomposition reaction of each compositional component, but it may run into a difficulty provided that tire components demonstrate similar thermal stability, thus leading to a complete superposition of peaks in a DTG curve. The subtraction method, however, can be applied after manipulating heating rate, since overlapped peaks can be separated by increasing or decreasing heating rate. Although the peak temperature and height (rate) in a DTG curve in the latter method were closely related to kinetic parameters of a single reaction, they can be rarely utilized to estimate the kinetic parameters of complex reactions because of disturbance arising from peak superposition.