Secondary organic aerosol (SOA) formation from branched alkanes (BAs) was simulated using the UNIPAR model, which predicted SOA growth via multiphase reactions of hydrocarbons, and compared with chamber data. Product distributions (PDs) of BAs were created by extrapolating PDs of linear alkanes (LAs). To account for methyl branching, an autoxidation reduction factor was applied to PDs. BAs in diesel fuel were shown to produce a higher proportion of SOA compared with LAs.