Cr-poisoning at an SOFC cathode was investigated by using the patterned thin film model electrode of La0.6Sr0.4CoO3-δ on a Ce0.9Gd0.1O1.95 electrolyte. The model electrode was exposed to Cr-containing oxygen gas for a week at 973 K while applying the cathodic bias. After the Cr-poisoning test, the surface morphology and the distribution of Cr were examined by means of SEM and SIMS. Deposition of Cr-containing particles was observed on the electrode surface preferentially near the electrode/electrolyte interface. This result demonstrated that the cathodic polarization accelerated the Cr deposition especially at the area where the cathodic reaction took place.