The c-axis oriented hcp-Co83Ir17 soft magnetic thin films with in-plane uniaxial anisotropy and negative magnetocrystalline anisotropy (K-u(grain)) were fabricated at 500 degrees C, and thickness dependence of their high-frequency magnetic properties was investigated. Both the saturation magnetization and K-u(grain) are improved compared with those of the samples fabricated at room temperature in previous reports. As the introduction of negative K-u(grain), the natural resonance frequency is improved without affecting the initial permeability. With CoIr thickness increasing from 55 nm to 270 nm, the initial permeability decreases slightly; the natural resonance frequency increases and then changes little; the damping constant decreases gradually. (C) 2014 Elsevier B.V. All rights reserved.