This paper described how to estimate the Arrhenius parameters as well as the pyrolysis reaction model of LLDPE from isothermal kinetic data. We used a custom-made thermobalance that is capable of monitoring a weight decrease with time under pure static condition and performed six isothermal kinetic experiments at 713, 718, 723, 728, 733, and 738 K that were chosen within a temperature range (710-740 K) where main decompositions were observed from non-isothermal kinetic results. Comparing experimental reduced-time-plots (RTPs) with theoretical ones, the pyrolysis reaction model of LLDPE is accounted for by "Avrami-Erofeev" model in the investigated temperature region, allowing its functional form to be 2(1 - alpha)[- In(1 - alpha)](1/2). It is, hence, expected that the reaction order model adopted by the previous studies without verification is inappropriate to represent the pyrolysis reaction model of LLDPE. Bubble nucleation may be a major pyrolysis reaction mechanism of LLDPE. As heat is applied, the LLDPE is melted. Volatiles may be accumulated inside the melt until reaching a critical concentration where bubble nucleation sets forth. The rates of heat, mass, or momentum transfer in the LLDPE melt and its physico-chemical properties (especially viscosity) play an important role in characterizing the thermal decomposition kinetics of LLDPE.