Oily substances extracted by a crude process from the stem including its bark (hereafter referred to as the stem) of Dodonaea viscosa (L.) Jacq. has been used by practitioners of traditional Indian medicine to treat inflammation, pain and other musculoskeletal disorders. The aim of this study is to understand the scientific phenomena behind the process adopted by traditional practitioners for extraction and to establish the principle of extraction process by a simulated scientific method. The study also investigates the phyto-chemical composition of the extracts and compares the simulated extract with the traditional extract. The traditional method was subjected to a detailed analysis, and it was identified as a crude equivalent of pyrolysis. The process was simulated under controlled conditions in a self-fabricated prototype pyrolyser. The extracts from both methods were compared for their compositional identity and phytochemistry using FT-IR and GC-MS. The results show that in both the cases, the presence of dihydroxy, dimethyl and other substituted catechols, which are postulated as pyrolysate derivatives of the anti-spasmodic flavonoids quercetin, rutin, kaempferol and sakuranetin. The applied principle of extraction is identified as slow pyrolysis, which is supported by the visual and chemical similarities of the extracts from both methods. The phyto-chemical analysis indicates the presence of anti-spasmodic chemicals in the extract from the stem of Dodonaea viscosa (L.) Jacq.; these chemicals are likely the active substances in the treatment of inflammation, pain and other musculoskeletal disorders, and the research substantiates the stem's historical use by traditional practitioners.