An innovative combined desulphurization/denitration (DeSO(x)/DeNO(x)) process was tested in this study. It utilizes the so-called powder-particle fluidized bed (PPEB) to co-fluidize continuously supplied fine DeSO(x) sorbent (several to tens of micrometers) and coarse DeNO(x) catalyst (several hundreds of micrometers), the fluidization medium particles. Ammonia for NOx, reduction is fed to the system from the bottom of the bed. Thus, SOx and NOx are removed simultaneously from flue gas, used as fluidizing gas, in a single reactor. By using model gases containing SO2 and NO, the removal efficiency of this process was examined in a laboratory PPFB reactor with respect to choices of DeSO(x) sorbents and DeNO(x) catalysts, reaction temperature, and major gas components. At a reaction temperature of 623 K and a static height of the catalyst bed of 0.1 m, removals greater than 90% for SO2 and about 80% for NO were achieved with the sorbent CuO . V2O5. K2SO4/Al2O3 (at Cu/S = 1) and the catalyst V2O5. WO3/TiO2 or WO3/TiO2 (at NH3/NO = 1) for a simulated flue gas SO2-NO-H2O-N-2-air consisting of oxygen 2 vol.%, water vapour 0-10 vol.%, SO2 500 ppm and NO 500 ppm. These removals are expected to be further improved by avoiding poisoning by such a copper oxide sorbent on NOx reduction. The possible industrial application of this process is also discussed.