Highly crystalline Ce0.8Sm0.2O1.9 (SDC) nanoparticles were synthesized via a polyacrylamide hydrogel assisted combustion process involving microwave-induced gelation and combustion. Crosslinked polyacryamide was used as fuel, and uniform dispersion of ceramic precursors in the porous polyacrylamide hydrogel led to mild combustion and limited agglomeration of ceramic particles. The combustion method developed here prolonged combustion process, and allowed ceramic particles to further crystallization. As-synthesized powders were calcined to increase particles size, for the purposed of reducing sintering shrinkage in the densification of electrolyte film. The reactive SDC powders with particle sizes of 0.1a??1 I?m were made into dense solid oxide fuel cell (SOFC) electrolyte film by dip-coating. The cell with a 6 I?m thick SDC film achieved high maximum power densities of 353 and 533 mW cma??2 at 550 and 600 A?C, respectively.