Layered phyllosilicate fillers have received the attention in the polymer industry due to their unique sheet-like structure in nanoscale. The addition of a small amount of bentonite nanofiller leads to the improvement of mechanical, thermal, and gas barrier properties of rubber polymers. Depending on the application, the natural bentonite is often modified by physical processes or chemical processes (intercalation, cation exchange process, functionalization, pillaring, etc.). The chemical modification increases the size of the interlayer spaces and provides the hydrophobic environment. Functionalization (e.g. silanization), which encompasses the chemical grafting of thermally stable silane coupling agents onto the clay platelets, make the inorganic bentonite and the organic polymer matrix compatible. In the presented study, the commercial P130 bentonite from Lieskovec deposit was modified by silanization. For characterization of raw bentonite as well as modified bentonite samples, the infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. Modified P130 bentonite was added to the natural rubber matrix to study the influence of silane functionalizated bentonite on the curing characteristics (M_L, M_H, t₉₀, R_v) and mechanical properties (TS_b, E_b hardness) of polymer composites. Raw and modified bentonite were mixed into the rubber blend in particular ratio of 10, 15, 20 phr in various combination with silane agent, Perkasil and carbon black. The highest maximum torque values were obtained with the sample using 15 phr of silanized P130. The tensile strength (TS_b) and hardness values decreased with increasing of non-silanized as well as silanized P130 content. However, when silanized P130 was used, the values of TS_b were higher in comparison with non-silanized P130. The most enhanced properties of rubber blends were found with the addition of 5 phr modified bentonite filler P130.