Microfluidic biofuel cell (micro-BFC) stacking is a strategy to improve the power output of micro-BFC. There are limited reports on micro-BFC stacking, although they usually study either series or parallel configurations. Here we report on a micro-BFC stack comprising four cells connected with various configurations, e.g., individually, series, parallel and series/parallel. Electrodes modified with glucose dehydrogenase and bilirubin oxidase were used as bioanode and biocathode, respectively. A single cell generated an open circuit potential (OCP) of 0.78 V with a current density and power density of 1.37 mA cm(-2) and 0.36 mW cm(-2), respectively. The OCP voltage enhanced further to 1.27 V when the four cells were connected in series and a density current of 0.78 mA cm(-2). When the four cells were connected in parallel, the current density and power output increased to 2.0 mA cm(-2) and 0.58 mW cm(-2). A combined series/parallel configuration was also evaluated, yielding a maximum OCP of 1.23 V, although the current density and power output remained unchanged around to 0.95 mA cm(-2) and 0.42 mW cm(-2), respectively. This type of micro-BFC stacking presents a new strategy for obtaining improved voltages and power outputs without the requirement of any external electronic device.