In present communication, waste frying oil (WFO) has been used as a feedstock for biodiesel synthesis. WFO, procured from a local Indian restaurant possessed an acid value of 0.84mg KOH/g, which is low enough for single step transesterification reaction. Biodiesel (fatty acid methyl esters) was washed after transesterification reaction and the yield got lowered substantially (from 96% to 86.36%) after water washing owing to loss of esters. 30:100vol% (methanol to oil), 0.6wt% NaOCH3, 60 degrees C temperature and 600rpm agitation in 1h reaction time was found to be optimum for transesterification reaction. 1H NMR spectrum showed a high conversion (95.19%) of fatty acids in WFO to biodiesel in 2h reaction time. Almost complete conversion (99.68%) was attained in 2h reaction time. (C) 2011 Canadian Society for Chemical Engineering