The paper reports on the structure, mechanical and optical properties of sputtered Zr–Al–O films. The Zr–Al–O films with Zr/Al>1 and Zr/Al<1 were prepared by a reactive sputtering using ac pulse dual magnetrons. The magnetrons were equipped with a target composed of Al plate (∅=50mm) fixed to the magnetron cathode by a Zr fixing ring with inner diameter ∅ in . The content of Al in the Zr–Al–O film was controlled by ∅ in . It makes possible to control effectively the structure of the Zr–Al–O film determined by a mixture of the crystalline ZrO 2 phase and the amorphous Al 2 O 3 phase. The effect of Al content on the structure, mechanical and optical properties of the Zr–Al–O film is investigated in detail. It was found that (i) the Zr–Al–O films with Zr/Al<1 are X-ray amorphous and exhibit low hardness (H≤13GPa), an effective Young's modulus E ⁎ resulting in a low H/E ⁎ <0.1 ratio and low elastic recovery W e ≤60 and (ii) the Zr–Al–O films with Zr/Al>1 are crystalline and exhibit high hardness (H=18 to 19GPa), an E ⁎ satisfying a high H/E ⁎ ≥0.1 ratio, high W e up to 78% and strongly enhanced resistance to cracking during bending even for thick films up to 5μm.