Recent studies in our laboratory have shown that a range of A-site deficient perovskite oxides, with carefully tuned chemical compositions, exhibit excellent properties when used in devices such as solid oxide fuel cells. The key to this performance is the migration of cations from the bulk single phase material, forming a catalytically active secondary phase, under reducing conditions in an ‘exsolution’ process. Recent work in our laboratories has shown that the exsolution may also be induced by electrochemical poling, which has enhanced performances even further. The aim of this work is to study the electrochemically induced exsolution in-situ and compare it with ‘conventional’ exsolution under reducing conditions, whilst also probing the crystal structure of these A-site deficient perovskites.