Siloxane polymers are widely used in various areas of technology due to the combination of properties manifested in this class of polymers: flexibility, chemical and biological inertia, resistance to UV radiation, thermal stability, biocompatibility [1]. Also polydimethylsiloxanes are elastomeric polymers that can be used for building flexible membranes with low value for Young modulus and can be used as such in electromagnetic actuators devices [2]. Such siloxane elastomers manifest larger forces and displacements when compared with electrostatic or piezoelectric actuators. This research presents the preparation and characterization of dielectric elastomer films with increased dielectric constant for future use in actuators and energy harvesting. As matrix for the elastomers was used a polydimethylsiloxane- α,ω -diol with molecular mass Mn=356 000 which were custom prepared in our laboratory by cationic ring opening polymerization. The polysiloxanes were chosen for this study due to the combination of their properties mentioned before, which make them suitable for use in environments with different atmospheric and chemical conditions. Iron oxide nanoparticles smaller than 100 nm (prepared in our laboratory) were incorporated as disperse phase after which the mixtures were processed as films and crosslinked by condensation tehcnique with methyltriacetoxysilane. The iron oxide nanoparticles were characterized by energy-dispersive X-ray spectroscopy, wide-angle X-ray diffraction and transmission electron microscopy, while the composite materials were characterized by FTIR spectroscopy, dielectric spectrometry, energy-dispersive X-ray spectroscopy. The results of investigations certified the homogeneous dispersion of nanoparticles in the siloxane matrix. The use of iron oxide nanoparticles had beneficial effects for the properties of the final elastomer films: the addition of small percentage (10%) of nanoparticles leads to elastomer samples with increased breaking strain, the value of the dielectric constant increased from 3 for pure silicone up to 6.1 for the elastomer with nanoparticles, while the conductivity increased from la 3 · 10-14 up to 10-13 S/cm, and thus remained in the range for dielectric materials.