The thermal characterization of industrially extruded PVC tubes (unloaded and loaded with micronized palm kernel shell powder) has been carried out according to the standard. The aim of this work is to elaborate mathematical models for the calculation of the experimental thermal properties of PVC tubes as a function of the shell powder dosage. We performed the TGA/DSC of unloaded PVC tubes and PVC tubes loaded with 12.54%, 32.03% and 51.01% of palm kernel shell powder using a TG coupled DSC apparatus of LENSEI brand. We obtained the TG/DSC thermograms and their recording which gave us the results of the thermal characteristics of the tubes. From those results, we obtained that the phase transition temperatures vary with the dosage. We have represented the curves of heat absorption as a function of the mass decrease. We have obtained that the kernel shell powder allows the PVC to absorb a large amount of heat before burning, creating relaxation phenomena. From these results we elaborated mathematical models to calculate the thermal characteristic parameters of the PVC tubes as a function of the dosage with the kernel shell powder. We obtained that all the equations are polynomial mathematical laws of degrees 3 (three), when the coefficient of determination R2 is 1 (one), justifying the influence of the palm kernel shell powder on the thermal properties of PVC tubes.