1 Layered Microstructures based on BaZr 0.85 Y 0.15 O 3-δ by Pulsed Laser Deposition for Metal Supported Proton Ceramic Electrolyzer Cells Elena Stefan 1* , Marit Stange 2 , Christelle Denonville 2 , Yngve Larring 2 , Nicolas Hildenbrand 3 Truls Norby 1 and Reidar Haugsrud 1 1 University of Oslo, Department of Chemistry, FERMiO, Gaustadalléen 21, NO-0349 Oslo, Norway 2 SINTEF, Forskningsveien 1, NO-0373 Oslo, Norway 3 Solmates BV, Drienerloolaan 5, Building 46, 7522NB, Enschede, the Netherlands E-mail addresses: elena.stefan@smn.uio.no; marit.stange@sintef.no; Christelle.Denonville@sintef.no; Yngve.Larring@sintef.no; Nicolas.Hildenbrand@solmates.nl; truls.norby@kjemi.uio.no; reidar.haugsrud@smn.uio.no * Corresponding author. Tel.: +47 22 85 77 59; fax +47 22 84 06 51. Abstract Planar metal-supported cell designs provide cost-effective scaling-up of solid oxide fuel cells and electrolyzers. Here, we report on the fabrication of a BaZr 0.85 Y 0.15 O 3-δ –NiO (BZY15-NiO) composite electrode and BaZr 0.85 Y 0.15 O 3-δ (BZY15) proton conducting electrolyte films on metal and ceramic substrates using pulsed laser deposition (PLD). The results demonstrate successful sequential deposition of porous electrode and dense electrolyte structure by PLD at moderate temperatures, without the need for subsequent high temperature sintering. The decrease in roughness of the metal substrate used for deposition by spray-coating intermediary oxide layers had significant importance to the fabrication of functional layers as thin films. Crystalline porous BZY15-NiO and dense BZY15 films were sequentially deposited at high substrate temperature on metal supports (MS) with or without an electron-conducting barrier oxide layer, e.g. MS/(BZY15-Ni)/(BZY15-NiO)/BZY15 and MS/CeO 2 /(BZY15-NiO)/BZY15. The different microstructures for electrode and electrolyte were achieved with deposition steps at different substrate temperatures (800, 600 °C) and a gradual decrease of the pressure of O 2 in the deposition chamber. Keywords: pulsed laser deposition (PLD), thin films, sequential deposition, metal support, proton ceramic electrolyzer cells (PCEC).