In this study, ethyl and methyl esters of black mustard (Brassica nigra L.) seed oil using NaOH and KOH were produced. To attain the optimum condition for biodiesel production from black mustard oil, varied catalyst quantity, alcohol amount, reaction temperature, and reaction time were explored and applying polynomial regression method (PRM) adopted. The minimum biodiesel yield was obtained as 96.229% using 45.12 wt% ethanol and 0.838 wt% KOH by weight of oil at 56 min reaction time, and 35.4 degrees C reaction temperature. On the other hand, the maximum biodiesel yield was achieved to be 97.335% utilizing KOH of 0.4 wt% and methanol of 20.39 wt%, at the reaction temperature of 57.1 degrees C, and reaction time of 54.1 min. The increase in biodiesel yield was determined to be on the order of 1.4380, 0.0814, 0.0548 and 0.4352% for NaOHMB, KOHMB, NaOHEB, and KOHEB, respectively, with PRM. Consequently, it can be stated that in comparison with the classical method, PRM is a more promising optimization technique in order to get a higher biodiesel yield. (C) 2020 Elsevier Ltd. All rights reserved.