Long-life packages are composed by two main materials: paper and low-density polyethylene (LDPE) with aluminium composite. Usually, the packages are disposed in landfills, generating an environmental impact due to its increasing consume. Recycling could be a solution if the recycled and raw materials used in the production have the same properties, being necessary to perform tests to identify the similarities and differences of each material. This study aims the study of thermal decomposition behaviour and kinetic parameters estimation of raw and recycled long-life packages low-density polyethylene using thermogravimetric analysis (TGA) under inert condition in temperature range of 25 – 700 °C. Classical methods, for example Kissinger and Ozawa, depend on many heating rates to determine kinetic parameters. Stochastic global search algorithms, such as Genetic Algorithm (GA), have great potential in parameter estimation using only one heating rate. The software Matlab 2018b was used to calculate all the models and the efficiency was evaluated using the determination coefficient (R²). The results showed a difference in the reaction order but similar pre-exponential and activation energy values.