Quad-crystal Co/NiAl/Ag thin films were epitaxially grown on hydrofluoric acid etched Si(111) single crystal substrates by sputter deposition. The orientation relationship was studied by x-ray 0/20 diffraction and pole figure Φ-scan, and it was determined to be Co(1011) ‖ NiAl(110) ‖ Ag(111) ‖ Si(111). The Ag layer contains two twin-related orientations of grains. NiAl grows with three variants of grains on the Ag(111) layer. Since Co(1011) contains grains with four possible easy axis directions when grown on each NiAl variant, the quad-crystal media consist of grains with twelve easy axis directions and exhibit nearly isotropic in-plane magnetic properties. Meanwhile, uni-crystal Co(1010)/NiAl(112) films were also epitaxially grown on Ag(110)/HF-Si(110) templates. The orientation relationships determined from these epitaxial films were very useful in understanding the texture evolution of the Co alloys on NiAl. It indicates that the Co (1010) texture evolution on the (110) texture of NiAl on amorphous substrates, such as NiP/AlMg or glass, is due to a difficult to observe NiAI (112) texture on the top of the (110) texture.