This soil burn and leachate data set was prepared to assess the impact of fire on soil leachability and potential ecological risks. Soils representative of major geological types, unaffected by fires, were collected from nine locations along the east coast of NSW: consisting of three sedimentary soil types: Cumberland State Forest, Lake Parramatta and Hat Head, two metamorphic soil types: Port Macquarie and Yarriabini National Park, three igneous soil types: Bellmore Falls (Budderoo), Robertson National Park and Middle Brother National Park, and one coastal plains organic soil: Crescent Head/Bellmore Swamp. The soils were characterised for metal and nutrient (N, P) levels and analysed using X-ray diffractometry (XRD) to determine their mineralogical composition. The soils were then subjected to a simulated fire impact experiment, where they were treated at temperatures of 200 °C (low-moderate severity), 500 °C (high severity), and 850 °C (extreme severity) for 30 minutes, along with an untreated control (unburnt). After cooling, the soils were leached using a modified version of the Toxicity Characteristic Leaching Procedure (TCLP) as outlined in the USEPA SW-846 Test Method 1311 in freshwater. Dissolved metals, total nutrients, and dissolved nutrients were sampled and analysed in the leachates. This data fed into a leachate assessment and a preliminary aquatic ecological risk assessment, with a report to be released soon. The data presented in this spreadsheet is: • initial characterisation data set for each soil including metals, nutrients organic matter and moisture content. • XRD data for the soils in unburnt, 200 °C and 850 °C treatments. • Leachate data for total nutrients, dissolved nutrients and dissolved metals.