This study examines the use of unstructured kinetic model and artificial neural networks as predictive tools for xylitol production by Debaryomyces nepalensis NCYC 3413 in bioreactor. An unstructured kinetic model was proposed in order to assess the influence of pH (4, 5 and 6), temperature (25 degrees C, 30 degrees C and 35 degrees C) and volumetric oxygen transfer coefficient k(L)a (0.14 h(-1), 0.28 h(-1) and 0.56 h(-1)) on growth and xylitol production. A feed-forward back-propagation artificial neural network ( ANN) has been developed to investigate the effect of process condition on xylitol production. ANN configuration of 6-10-3 layers was selected and trained with 339 experimental data points from bioreactor studies. Results showed that simulation and prediction accuracy of ANN was apparently higher when compared to unstructured mechanistic model under varying operational conditions. ANN was found to be an efficient data-driven tool to predict the optimal harvest time in xylitol production. (C) 2016 Elsevier Ltd. All rights reserved.