A membraneless sodium borohydride fuel cell has been fabricated using sodium borohydride as the fuel and sodium percarbonate as the oxidant in an alkaline and acid media configuration. Different operating conditions and different cell dimensions were used to assess the performance of this fuel cell. At room temperature, the laminar flow-based membraneless fuel cell was found to reach a maximum power density of 23.61 mW cm-² using 0.15 M sodium borate in 3 M sodium hydroxide solution as the fuel and 0.15 M percarbonate in 1.5 M sulphuric acid solution as the oxidant.