In the present paper, the methods of rotational viscometry and differential scanning calorimetry (DSC) studied the compatibility of PV-1 polyarylate with various epoxy resins. Of particular interest is this thermoplastic as a modifier due to the increased heat resistance. Materials based on it are obtained with higher heat-resistant and wear-resistant properties. The inter-solubility of the components requires attention, since this process greatly affects both the properties of the polymer composite material (PCM) and the method of obtaining the finished product. With poor compatibility of thermoplastics with reactoplastics, dispersion can be formed and uneven completion of exchange processes during processing, which can affect the structure and properties of the finished PCM. Due to the unpredictability of the initial factors, it is rather difficult to predict the behavior of the thermoplast, therefore, such issues are solved mainly in practice. The article investigated the behavior of mixtures of epoxy oligomers ED-20, UP-637, EN-6 and EHD, depending on the concentration of thermoplastic, as well as when comparing relative to each other. According to test results, it was found that, like other thermoplastic modifiers, PV-1 is dissolved in epoxy resins. However, unlike polyarylsulfones, the temperature range of this process shifts to higher temperatures due to the increased heat resistance of the thermoplastic compared to polyarylsulfones. A linear dependence of the thermoplastic dissolution temperature on its content in the mixture was found, as well as differences in the rheological behavior depending on the composition. It is shown that the regions of thermal effects on the DSC curves, which coincide with the regions of viscosity increase as they are heated, observed on the rheological curves, are not related to the chemical interaction, but to the process of dissolution. In addition, it was found that as a result of the combination, a gradual increase in viscosity occurs, especially at high temperatures.