Abstract Odour emissions from oil refineries are one of the important air pollution issues, which can limit the establishment or expansion of new or existing plants due to the complaints of nearby residents. Odour emissions accompanied by complaints can affect property values and, more importantly, the health of people living in adjacent areas. Developing suitable setback distances by considering appropriate odour impact criteria is one of the most effective approaches to avoid odour nuisance. However, a lack of knowledge surrounding the odour emissions and odour properties of oil refineries has made developing source-specific odour impact criteria and setback distance difficult. This study investigates odour dispersion from a conventional oil refinery plant in the surrounding environment using field measurements at 62 spots up to 7 km downwind of the plant, with measurements being taken in the spring and summer. Various odour properties of the oil refinery air emissions, including odour concentration (OC), odour intensity (OI), odour hedonic tone (HT), and odour character have been measured by adapting the relevant standards and using commonly applied methods from previous odour studies. Results show that odour can travel up to 7 km from the refinery under certain weather conditions. In general, a more stable atmosphere results in transporting odour from the plant to further distances in colder seasons, and lower wind speeds lead to higher OC in nearby areas. The study also categorizes the emitted odour into 5 limited characters, which can be used to identify compounds responsible for odour problems. The study finds an exponential relationship between OI and OC, and a linear relationship between OI and HT in which odour character does not play an important role. By providing an overview of oil refinery odour properties and radii of dispersion in the surrounding environment, the results of this study could provide jurisdictions with a scientific basis for setting odour impact criteria and setback distances from oil refineries.