There have been few studies to date focused on identifying the characteristics of Australian arsonists, and a distinct absence of any analyses of trends in arson offending over time. In order to address this gap, the current study reviewed sentencing transcripts obtained across all Australian jurisdictions between 1990 and 2015, to identify trends in the features of arson offending and key characteristics of the arsonists, over this 25-year period. Offender characteristics such gender, motivation, Indigenous status and degree of exclusivity–versatility of the arson offending were considered. Trend analyses indicated substance use, mental illness and female gender to be increasingly significant factors in the commission of arson offences over time. Significant differences were identified between Indigenous and non-Indigenous arsonists, which raises questions as to the adequacy of current theory to explain firesetting in this group.