Elastomer blends are used in many different industries from automotive to electronics and aviation. Blending of elastomers improves chemical, physical properties and processability of rubber products. One of the most commonly used rubber is natural rubber (NR). NR has high tensile and tear strength, and dynamic properties. On the other hand, butadiene rubber (BR) has better abrasion resistance and resistance to initiation of cracks. Due to the fact that dynamic heat generation of BR is less than NR, it is advantageous to use BR with NR. NR / BR blends have been mainly used in the production of vehicle tires, conveyor belts and suspension elements. Rubber blends are commonly used with certain fillers to enhance the mechanical properties and decrease the cost. Polyhedral oligomeric silsesquioxane (POSS) is one of the latest and popular nano-sized filler used for this purpose. POSS technology is regarded as one of the recent development in polymer science and technology. POSS molecules are considered as the smallest size for silica and they can be dispersed in the matrix at the nanometer level. POSS/polymer blends are hybrid materials formed by covalent bonding of functional groups to the main polymer matrix. POSS was used for various purposes in the literature, such as a reinforcing filler material to increase mechanical strength, corrosion inhibitor in paint and coatings, and flame retardant in polymers. In this study, NR/BR blends including different types and amount of POSS were prepared by using laboratory scale internal mixer. Vulcanization of blends were performed by using Moving Die Rheometer (MDR). Samples were analyzed by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to determine the difference in thermal properties. The rheological, mechanical and morphological properties were invesitgated. This study is granted by KOU BAP(Grant Number: 2017/121)