The production line and relevant technology for the processing of black tea in Australia have been modified from those currently employed in other tea producing countries. Thus, it is necessary to understand the changes in chemical composition occurring during the growing and processing of Australian tea, if quality improvements in tea are to be achieved. However, no published data are available relating the chemical composition, including phenolic compounds, to the growing and processing of Australian tea. Therefore, an investigation into the types and contents of flavonoids and other polyphenols in Australian grown tea at various growing seasons and made tea during different processing steps was carried out to provide the Australian tea industry with information to assist with maximising the quality of its black tea. Areas where quality could be improved were also identified.