Recently, unexpected physical (superconducting, electrical, and magnetic) properties have been found at the interface of oxide film hetero-structures. The investigation of oxide film hetero-structure ionic conductivity is receiving growing attention due to miniaturized solid state ionic device applications. This talk will present results on the electrochemical characterization of oxygen-ion conducting oxide thin-film superlattices and hetero-structures fabricated by pulsed laser deposition (PLD) to clarify the strain influence on the ionic conductivity. Ceria and zirconia superlattices were deposited on (001)-oriented MgO single-crystal wafers, using a thin buffer layer of SrTiO3 (STO) to allow epitaxial growth. We present also an unprecedented photoconductivity effect for SrTiO3/LaAlO3 (LAO) interfaces, one of the most investigated interface in the last decade, which is persistent even at room temperature and giant as it gives rise to a conductivity increase of about 5 orders of magnitude.