Thin film BaTiO3 capacitors were deposited by RF magnetron sputtering. The leakage current was suppressed by more than 3 orders of magnitude if a trace of hydrogen was introduced into the sputtering chamber during film deposition. The introduction of hydrogen gas during sputtering makes the dc conductivity as low as 1×10−13 (Ω−cm)−1 for the amorphous films but still gives the dielectric constant a value of around 17. However, this accomplishment could not be achieved for polycrystal BaTiO3 thin film capacitors. As the substrate temperature increased from room temperature to 700°C, the dielectric constant was increased from 16 to 300 by using Ar + O2 gas. But, the dielectric constant was only around 30 at a deposition temperature of 700°C while the leakage current was decreased when using a gas mixture of Ar + H2 + O2 during sputtering.