A study of the Ni/Zr system has been undertaken through x-ray reflectivity measurements of Ni-Zr alloy layers and a trilayer sample Ni/Zr/Ni, deposited by a home-built D.C. magnetron sputtering unit. Ni-Zr alloys are known to have high glass-forming ability in a wide range of concentrations and play a significant role in the study of bulk amorphous metallic materials. It was observed that the Ni-Zr alloy formed by co-sputtering was amorphous, and that no interfacial alloys were obtained in the analysis of the trilayer sample.