FIELD: chemical technology. SUBSTANCE: invention relates to preparing a filling agent. Filling agent comprises carbon phase and silicon- containing phase. Silicon-containing phase is on filling agent surface or it is distributed by all filling agent. For preparing filling agent the parent raw is added to the first step of multistep reactor. Another parent raw is added to reactor after the first step. One of raw sort comprises carbon and another raw comprises silicon compounds or their mixture with carbon raw. Silicon- -containing compounds are subjected for decomposition by pyrolysis of carbon raw to yield carbon black and a filling agent is formed. Filling agent can comprise metal-containing phase. Filling agent is a component of elastomeric composition. These compositions improve rolling resistance and cohesion under moisture conditions in tires. Filling agent shows unique structure. EFFECT: improved and valuable properties of filling agent. 92 cl, 1 dwg, 11 tbl
