Plasma spraying on gas turbine parts of thermal barrier coatings (TBC) is widely used today either to increase the turbine inlet temperature with consequent improvement of the efficiency or to reduce the requirements for the cooling system and increase components life-time. Development of low conductivity TBCs which allows us to further increase gas turbine efficiency and availability is a permanent challenge. In order to get low thermal conductivity values an experimental program has been organised. Two zirconia powders were used for coating deposition: yttria stabilised zirconia (YSZ) and dysprosia stabilised zirconia (DSZ). Microstructural analysis has been performed to evaluate the influence of the spraying parameters on the coatings morphology and porosity level. Two methods were utilised to evaluate the coatings thermal conductivity: Laser Flash (LF) and Transient Plane Source (TPS). Correlations were studied between the measured values of thermal conductivity (found with LF and TPS) as well as between coating structure/composition and its thermal conductivity.