VFA functionalization by the addition of hydroxylic group in the acidic chain would allow consecutive production of alternative biopolyesters else than microbial PHAs. In particular, the addition of the -OH function in the terminal C (omega-position) was explored by testing the activity on octanoic acid of two alkane/fatty acids degrading bacteria in a bioelectrochemical system. Two different bacterial strains were used for bioconversion tests: Pseudomonas oleovorans ATCC® 29347 and Bacillus megaterium ATCC® 14581. Dedicated bioelectrochemical reactors (BES) were designed and set up: they consisted of two gastight borosilicate glass bottles (total volume of 420 mL each) separated by a 3 cm2 cross-sectional area through a Nafion® 117 proton exchange membrane (PEM). Two different types of monooxygenases capable to hydroxylate alkanes and fatty acids were used. While in open circuit conditions (i.e., controls with no potential applied) both strains produce only traces of difunctional intermediates of octanoic acid degradation, a significant increase of the octanoic acid bioconversion into difunctional intermediates could be obtained with the application of a cathodic potential of -0.4 V vs. SHE, in particular with P. oleovorans and under resting cells conditions (macronutrients limitation). However, no exploitable results were obtained so far, since the application of bioelectrochemical systems to provide reducing power for the hydroxylation of VFA chain was not effective enough and no significant hydroxylated acid production was observed.