A Paramagnetic Oxygen Partial Pressure Sensor (ParaO) has been awarded to be part of the Environment Control and Life Support System (ECLSS) of the European Space Station Columbus. Therefore a development programme has been released, facing the delivery of fully space-qualified flying hardware. The sensor utilizes the paramagnetic effect of oxygen. Cross sensitivities to other gases are negligible. The sensor is able to withstand space vacuum. A Development Model with the main outlines equivalent to the flying hardware has been successfully put into operation.