Low-rank coals characterized by a high content of sulfur from Mequinenza (type III-S), Calaf (type III), and Utrillas (type III) basins, as well as type I-S oil shales from Ribesalbes were analyzed by thermogravimetry for deriving kinetic parameters from many TG curves recorded with different heating rates (5, 15, and 25 K/min) in maximum temperature of oil generation (T-max) using a equation defined by Zsako. These results are contrasted with those obtained by NLS (nonlinear least squares) algorithms which derive kinetic parameters nearby T-max from single TG curve. Furthermore, analytical determination of organic sulfur has allowed the comparison of different maximum temperatures of oil generation, as well as apparent activation energies, to establish general trends when different types of kerogen are compared. Finally, a method to compare the kinetic parameters at different heating rates (5, 15, and 25 K/min) is applied nearby the maximum temperature of oil generation (T-max) obtaining similar kinetic values and therefore concluding that the applied method is correct for these selected coals and oil shales.