A complex approach to the choice of color masterbatches for rigid PVC compounds dyeing directly during high-speed extrusion is proposed in this paper. The data is shown to improve the thermal stability of rigid PVC compounds with new organosilicon modifiers. To evaluate the characteristics of pigment masterbatches it is suggested to use differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which allow determining the thermal stability, structure and behavior of the pigment masterbatch upon heating. These results will allow creating a fundamental basis for the synthesis and development of new pigments and masterbatches, formulate the requirements for the characteristics and choice of masterbatches taking into account the formulation of the polymer composition