The adsorption of arsine by copper palladium alloys was studied using a high-throughput composition spread alloy film (CSAF) sample library. A CuxPd1-x, CSAF coupon that spanned the complete alloy composition space (x = 0-1) was prepared by an evaporative deposition technique. The coupon was exposed to AsH3 in a N-2 background at 288 degrees C in a small flow reactor. Arsenic uptake was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy (SEM-EDX), and micro X-ray diffraction (mu-XRD). Pd- and Cu-rich alloy compositions exhibited large surface concentrations of As after exposure to AsH3. In the Cu-rich alloy, composition and structure measurements suggest the formation of a Cu3As phase. Arsenic uptake at Pd-rich alloy compositions is consistent with Pd2As or Pd8As3 phases; structural results suggest Pd2As with a hexagonal structure. In contrast, over a wide range of intermediate compositions (x(Cu) approximate to 0.20-0.75), little As uptake was observed. These results contribute to a basis for rational design of sorbents for the capture of arsenic from fluid streams, and to an understanding of the stability of palladium copper alloy membranes employed for hydrogen separation from coal-derived syngas. This work illustrates the application of high-throughput approaches based on CSAF sample libraries that can be applied to a wide variety of materials development and optimization challenges.