Ethyl acetoacetate was investigated as a potential bio-based diluent for improving the cold flow properties of biodiesel from waste cooking oil. Waste cooking oil generally has relatively high saturated fatty acid content, meaning that the cold flow properties of the converted biodiesel are more challenging than the properties of biodiesel from conventional vegetable oils. The cold filter plugging point (CFPP) and pour point (PP) of biodiesel decreased after adding ethyl acetoacetate at 0%, 2.5%, 5%, 10% and 20% (vol). Both PP and CFPP decreased by 4 degrees C at 20 vol% ethyl acetoacetate. The effect of ethyl acetoacetate on kinematic viscosity, acid value and flash point was determined. Every sample satisfied ASTM 06751 except for the flash point (>= 10 vol% ethyl acetoacetate), but the 5 vol% blends were all acceptable. Oxidative stability was improved with the addition of ethyl acetoacetate. Overall, ethyl acetoacetate appears acceptable as a bio-based diluent for improving the cold flow properties of biodiesel. (C) 2013 Elsevier Ltd. All rights reserved.