The present work is definitely an approach towards attaining price competency of bio-diesel to petroleum diesel. The oils extracted from abundantly available waste of Zahidi, Basra and Khazravi date seeds were used to produce biodiesel using acid (HCl), base (KOH), immobilized enzyme (lipase), immobilized enzyme/acid (lipase/HCl) and immobilized enzyme/base (lipase/KOH) catalyzed processes. Mixed catalysis (immobilized enzyme + acid or immobilized enzyme + base) resulted in better yields in comparison to acid or base catalysis. The properties of biodiesel were evaluated by fuel standard tests and the results were compared with EN14214 and ASTM D6751 standards. Biodiesel produced from date seed oil was found to have a high cetane number (55-60.3), low iodine value (44-50) and good flash point (135-140 degrees C). Pour point of pure biodiesel produced from Khazravi and Zahidi was found to range from 2 to -2 degrees C. Biodiesel produced from Basra exhibited good pour point (-4.7 to -8.3 degrees C) in comparison to other varieties. The components present in biodiesel produced from various date varieties were determined by gas chromatographic-mass spectrometric analyses (GCMS). The fatty acid (%) detected in date seed biodiesel were oleic acid (33.4-47.4), lauric acid (19-28), palmitic acid (13.6-19.2), myristic acid (13.6-17.44) and linoleic acid (6.4-8.5). A special feature of date seed oil biodiesel was the presence of considerable amounts of low chain fatty acids. (C) 2015 Elsevier Ltd. All rights reserved.