The high operating temperature of solid oxide fuel cells (SOFC) brings about some restrictions like the high cost of fuel cell, long start-up time, thermal stress, and decreasing lifetime. Thus, lowering the operating temperature is vital for improvement of SOFC. However, reducing the operating temperature leads to some negative effects on solid oxide fuel cell performance by increasing the electrolyte and electrode resistances. This dissertation focuses on tailoring the cathode and/or electrolyte layers to obtain improved electrochemical performances. For this purpose, some strategies are proposed. These are (i) thin film cathode nanocomposite cathode layer formation, (ii) infiltration of porous GDC by LSCF/LSCF+GDC, (iii) infiltration of porous GDC by GDC solution to improve densification at lower temperature and finally (iv) electrochemical characterization of GDC densified by infiltration.