Barium titanate (BaTiO3) thin films doped with Mn (0.1-1.0 at%) were prepared by r.f. magnetron sputtering technique. Oxygen/argon (O-2/Ar) gas ratio is found to influence the sputtering rate of the films. The effects of Mn doping on the structural, microstructural and electrical properties of BaTiO3 thin films are studied. Mn-doped thin films annealed at high temperatures (700 degrees C) exhibited cubic perovskite structure. Mn doping is found to reduce the crystallization temperature and inhibit the grain growth in barium titanate thin films. The dielectric constant increases with Mn content and the dielectric loss (tan delta) reveals a minimum value of 0.0054 for 0.5% Mn-doped BaTiO3 films measured at 1 MHz. The leakage current density decreases with Mn doping and is 10(-11) A/cm(-2) at 6 kV/cm for 1% Mn-doped thin films.