In the present study, Sterculia foetida oil and waste cooking oil (SWO) were blended in a 1:1 ratio and its influence on biodiesel properties was studied. In situ transesterification for biodiesel production from blended oil and the investigational design were accomplished using an acid catalyst. Effects of process variables and operating conditions like sample amount, methanol volume, hexane volume, sulphuric acid, temperature and time were examined using Plackett–Burman design. GCMS revealed the presence of the linolenic acid (20.9%) and palmitic acid (18.3%) in maximum content and the high yield of biodiesel obtained from this blended oil from the experiments was around 95%. Sulphuric acid, temperature, time and hexane volume were found to be important process parameters as per the results obtained from the Plackett–Burman design. ANOVA analysis exhibited all the process parameters were significant except methanol volume and sample amount. The R2 value exhibiting 96.37% and R2 (adj) 92.02% shows the good fit of the model from the obtained regression equation. After in situ transesterification, the conversion of oil in to biodiesel is confirmed by FTIR analysis by the presence of band at (1741 cm–1). © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.