The recycling of steel plant by-products is a critical issue that needs thorough assessment and development for the sustainability of the integrated steel plant, from both environmental and economical perspectives. Research is being undertaken in the Steel Research Hub that aims to realise the value of by-products to the Australian steel industry and minimise the amount of by-product going to long term stockpile. As the first step, dust from basic oxygen steelmaking (BOS), a major steel plant by-product stream, is being characterised so that its potential use on plant or elsewhere can be assessed and evaluated. BOS dust contains components including iron, flux and zinc units, which have value on plant and elsewhere. Realising this value by recycling or other processing will help to minimise emissions and reduce costs by replacement of raw materials. However, some components, such as zinc, can limit the amount of possible recycling within the steel manufacturing process, causing both process and/or occupational health and safety issues. In this paper, characterisation of the BOS dust by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis, X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and differential calorimetry (DSC) is presented and discussed with a view of understanding the behaviour of the materials in use and on plant and its limits for further processing.