Abstract: ZnFe2O4 nanocatalysts synthesized by microwave combustion method is employed for biodiesel production from waste cooking oil (WCO). The zinc ferrite samples are prepared by varying the microwave power from 500 to 1500 W. The nanocatalysts are characterized by XRD, FTIR, DRS, HR-SEM and VSM techniques. Transesterification of WCO are investigated and maximum biodiesel yield of 98.6% is achieved with 4 wt% of ZnFe2O4 nanocatalyst (ZF-1500 sample), methanol/oil molar ratio of 21:1, reaction temperature about 60 °C and reaction time 1 h. The nanocatalyst (ZnFe2O4) was reused at least for 10 times. The activation energy (Ea) and frequency factor (A) is calculated to be 59.4 kJ mol−1 and 1.66 × 108 min−1 respectively. The thermodynamic parameters ∆H and ∆S were found to be 88.76 kJ mol−1 and − 0.096 kJ mol−1 K−1. The positive values of ∆G for transesterification process is found to be non-spontaneous and endergonic. Graphic Abstract: [Figure not available: see fulltext.] © 2019, Springer Science+Business Media, LLC, part of Springer Nature.