The electrochemical reactivity of molecular nitrogen is demonstrated by incorporation into yttria stabilized zirconia (YSZ) solid electrolyte upon cathodic polarisation at an intermediate temperature of about 700 degrees C. The nitrogen doping/incorporation (nitridation of YSZ) can be spatially controlled, as it only occurs in the vicinity of the electrode. The influence of the electrode material and the dopant (yttria) concentration is discussed. The I-E characteristics suggests a complex process (N-2 + 6e(-) = 2N(3-)) proceeding via a sequence of reaction steps. The electrochemical nitrogen doping is proven by secondary ion mass spectrometry. (c) 2006 The Electrochemical Society.