The development of a zero-gap alkaline water electrolysis stack based on a heterogeneous anion-selective polymer electrolyte membrane is reported. A bipolar electrode arrangement was selected as the most appropriate one. The design was targeted to verify the suitability of the membrane electrode assembly design and the functionality of the gas separator system developed together with the purity of the gases produced. The influence of various operational regimes on the purity of the gases was investigated. Last, but not least, a validation of the mathematical model to be used for scale-up of the cell, foreseen for the next step of the project, was performed.