The kinetic parameters for the thermal decomposition of 20 natural Turkish limestones, including the activation energy, pre-exponential factor and mechanism, were determined from their non-isothermal TG data. Thermogravimetric measurements were made in pure N2 and in a mixture of 15% CO2 and 85% dry air, at a constant heating rate of 10 K min-1. A computer program written in BASIC was used to evaluate the kinetic parameters of the decomposition reactions from experimental TG data. Five different calculation methods were employed in the kinetic analysis of the TG curves of the samples; this analysis also incorporated 14 different model equations reported in the literature concerning solid state rate-controlling mechanisms. It was observed that the values of the kinetic parameters showed differences depending on the method of calculation, the gaseous atmosphere and the sample properties.