Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) modeling were used to investigate the effect of power density and Columbic efficiency (CE) in a microbial fuel cell. Four influential factors, including ionic strength, initial pH, medium nitrogen concentration, and temperature were selected as operating variables. Five levels are used for every factor. A feed forward neural network was trained using the back propagation algorithm and Levenberg Marquardt algorithm. Besides, an adaptive neuro-fuzzy inference system (ANFIS) model for simulation this process has been utilized. The results revealed that for predicting power density and CE values both ANN and ANFIS model have acceptable performance (R-2 > 0.99), but ANN model has simpler structure and tuning procedure. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.