The advanced composites market in 2015 was valued at $16.67 billion, while it is predicted to reach to $23.52 billion by 2020. This substantial increase in the global composite market signifies the growing importance of composites and their widespread potential applications. Among all advanced composite applications, the production of polymeric composites with high thermal conductivity and low dielectric constant has been attracted great attentions for various applications. Different filler materials have been used and studied for such purposes. One of such filler materials are boron nitride particles which besides thermal conductivity and electrical resistivity [1,2], possess a number of special characteristics, such as mechanical strength, thermal stability, optical clarity, piezoelectric characteristics, and radiation shielding [3]. To investigate the structural effects of boron nitride particles on the morphology, and so the final properties of boron nitride nanocomposites, we have studied boron nitride nanotube (BNNT) and hexagonal boron nitride (hBN) in this study. In this project, we have focused on the development of thermally conductive yet electrically insulating polymeric boron nitride nanocomposites suitable for such applications, as microelectronic packaging, thermal management, and power generation. [1] Zhi, C. Y.; Bando, Y.; Terao, T.; Tang, C. C.; Kuwahara, H.; Golberg, D. Adv. Funct. Mater., 19, 1857−1862 (2009). [2] Yu, C.; Zhang J.; Tian, W.; Fan, X.; Yao, Y. RSC Adv., 8, 21948–21967 (2018). [3] Kim, K. S.; Kim, M. J.; Park, C.; Fay, C. C.; Chu, S.-H.; Kingston, C. T.; Simard, B. Semicond. Sci. Technol., 32, 013003 (2017).