Arsenic (As) is a class I toxic metal(loid) and classified as a human carcinogen. Arsenic contamination in soil has become a major environmental problem worldwide. Many As polluted sites have been reported around the world due to anthropogenic activities, especially mining and smelting operations. In Australia, extremely elevated levels of As have been associated with mine impacted soils, cattle dip sites and railway corridors. Abandoned mining sites are often in close proximity to agricultural land and sensitive ecological areas, such as National Parks. Thus, soil As mobility and bioavailability needs to be managed to reduce offsite migration and potential impacts to proximal receptors. In situ remediation of As contaminated soils is increasingly sought after, yet there are limited options available which are not highly sensitive to changing redox conditions. In this study, we have investigated the efficacy of zirconium (IV) to immobilize As in soil. Twelve As contaminated soils were collected from abandoned mine sites from different areas of Australia. The total As concentration in these soils ranged from 8.3 to 94,000 (median 490) µg/g. Soils were treated using either Milli-Q water or zirconyl chloride solution (soil : solution = 1 : 5) and allowed to react for 6 h. Following the adsorption step, the pH was adjusted to approximately 7 using 0.1 M NaOH, thus precipitating ZrO on the surface of soil colloids. Soils were then equilibrated (10mM NaNO₃) for 24 h, soil suspensions centrifuged, filtered (0.22 µm pore size) and analysed for As by inductively coupled plasma mass spectrometry (ICP-MS). All analyses were performed in duplicate. Arsenic extractability in untreated soils ranged from 0.9 to 347.8 (median 5.4) µg/g whereas ZrO treated soils ranged from 0.06 to 73.97 (median 0.17) µg/g. The results revealed that ZrO immobilization efficiency of As from polluted samples ranged from 79 to 93%, depending on the soil characteristics. In conclusion, ZrO shows potential for in situ immobilization of As in As contaminated soils. Further research is currently under way to investigate the use of mixed-metal composite frameworks and long-term efficacy in contaminated soils.