In this research iron manganese oxide nanocomposites were prepared by co-precipitation, sol-gel and mechanochemical methods by using iron (III) nitrate, iron (II) sulfate and manganese (II) nitrate as starting materials. These nanocomposites were prepared in the presence of various catalyst beds. The polyvinyl pyrrolidon (PVP) was used as a capping agent to control the agglomeration of the nanoparticles. Nanocatalysts were identified by FT-IR, XRD,SEM and TEM. The sizes of nanoparticles were determined by XRD data and Scherer equation. The prepared nanocatalysts were tested for decomposition of hydrogen peroxide. The hydrogen peroxide decomposition activity of samples was determined by evolved oxygen volumetry technique. Also based on surface area analysis and BET data, using of sodium metasilicate bed led to the high surface area and catalytic activity. Therefore Coprecipitation method in the presence of sodium metasilicate introduce as preferred method. To optimize the catalytic activities of nanoparticles factors such as concentration, cations ratio, pH and calcination temperature were investigated.