An ion assisted deposition technique, called Reactive Partially Ionized Beam (RPIB) deposition, was used to prepare amorphous BaxTi2-xOy thin films at a low substrate temperature (<60°C). The stoichiometry of the films varied from ×=l.0 for BaTiO3 to ×=0.2 for Ti-rich films. The optical, thermal, and broadband electrical properties of this class of thin film dielectrics were systematically studied. A lμm BaxTi2-xOy film is optically transparent with a band gap of 4.6eV. Both transmittance and bandgap decrease when the films are increasingly enriched with Ti. The Ti rich films remain amorphous at 600°C while the stoichiometric BaTiO3 crystallizes into the perovskite structure. Annealed Ti rich films are thermally stable (>700°C) with low leakage (<0.lμ/cm2 at 0.5MV/cm) and moderately high dielectric constant (εr = 15-35). Polycrystalline BaTiO 3 deposited at 600°C on a Pt/Ta/SiO2/Si substrate has an εr = 400. Capacitor structures with various metallizations were used to evaluate the dielectric properties, such as breakdown strength, leakage, εr and tanδ from DC to 600MHz. A generic test vehicle was designed and fabricated to extend the frequency domain characterization of the dielectrics up to 40GHz. No dispersion of εr was observed in this frequency range for amorphous BaxTi2-xOy.