Focus of this study is to observe the stirring effect on electrode distances by using Chlamydomonas reinhardtii transformation F5 in photo microbial fuel cells (PMFCs). The electrode distances applied in this study were 10.3, 12.5 and 14.7 cm, respectively. Higher power density and lower internal resistance were observed at electrode distance of 14.7 and 10.3 cm compared to at electrode distance of 12.5 cm. Despite of it, higher exchange current density (i(o)) and over potential (eta) but lower electron transfer coefficient (beta) can be observed at electrode distance of 14.7 and 10.3 cm compared to electrode distance of 12.5 cm. Since the results observed in the present study are different from some reported studies, the explanations are discussed in this paper. In addition we also performed experiment with different stirring speed and found out that power density increased and internal resistance decreased with the increasing stirring speed. (C) 2012 Elsevier Ltd. All rights reserved.