The study modelled the methane generation for a landfill in a tropical climate in Brazil, adjusting the values of the parameters of Methane Generation Potential (Lo) and Decay Constant (k), using the IPCC numerical model and LandGEM and Biogas (CETESB) software. Adopting published data from Cell 6 (C6) of the Metropolitan Center Sanitary Landfill, 15 combinations of k and Lo were performed to determine the ranges of values that best represented the generation of CH4. The results of the study allowed to conclude that values of k between 0.1 and 0.15 year−1, and Lo between 60 and 70 m³/t, resulted in simulations with good capacity to predict CH4 for the chosen landfill, obtaining errors lower than 30%. Furthermore, these intervals identified a better representation of CH4 generation for values of k equal to 0.15 year−1 and Lo equal to 60 m³/t. This combination showed estimation errors smaller than 6% when compared to CH4 measured at C6 between 2004 to 2009, showing the importance of having experimental values of k and Lo to adjust the simulations and calibrate the used tools.