Triglyceride autoxidation using a homogeneous Co/Mn/Zr/bromide catalyst in acetic acid (93%) of low grade tallow, canola oil or soy bean oil in a batch reactor at 150 degrees C for 2h, produced lower molecular weight products relative to the fatty acids of the starting triglycerides. For the autoxidation of tallow the main products after esterification were monoesters Me(CH2)(m)C(O)OMe (m = 5-12) and diesters MeOC(O)(CH2)C(O)OMe, (n = 7-12). Oxidation of the saturated fatty acids in triglycerides was confirmed and modelled using methyl palmitate. Post-treatment esterification of tallow autoxidation products to produce biodiesel (BD) esters resulted in improved cold temperature properties by a mean of 13.0 degrees C, i.e. a mean cloud point (CP) 1.0 degrees C (cf unmodified tallow biodiesel: CP 14 degrees C). (C) 2014 Elsevier B.V. All rights reserved.