A simple method was proposed for preparing aggregates of Pd nanoparticles on graphene oxide (GO) by mixing of palladium acetate and GO modified with polyhedral oligomeric silsesquioxane (POSS) (POSS-modified GO) in methanol. Spherical aggregates of Pd nanoparticles with a diameter 10-30 nm were densely produced on the surface of POSS-modified GO. POSS-modified GO was synthesized by the ionic interactions between negatively charged GO and positively charged POSS-NH3 (+). POSS-NH3 (+) with silica-like core and eight organic functional groups on the surface of GO plays a role in making the spherical aggregates of Pd nanoparticles (Pd-POSS/GO). The residual content and thermal stability of Pd-POSS/GO were higher than that of GO and POSS-modified GO in thermogravimetric (TGA) analysis. The size of aggregates of Pd nanoparticles on the surface of POSS-modified GO is smaller than that of aggregates of Pd nanoparticles produced without GO template. POSS-modified GO and Pd-POSS/GO were fully characterized by Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, and TGA.